diff --git a/simplexmq.cabal b/simplexmq.cabal
index 20c24059d..6b126d2eb 100644
--- a/simplexmq.cabal
+++ b/simplexmq.cabal
@@ -103,7 +103,6 @@ library
       Simplex.Messaging.Agent.Store.SQLite.Migrations.M20231225_failed_work_items
       Simplex.Messaging.Agent.TAsyncs
       Simplex.Messaging.Agent.TRcvQueues
-      Simplex.Messaging.Builder
       Simplex.Messaging.Client
       Simplex.Messaging.Client.Agent
       Simplex.Messaging.Crypto
diff --git a/src/Simplex/FileTransfer/Client.hs b/src/Simplex/FileTransfer/Client.hs
index 9b5973edd..9109de789 100644
--- a/src/Simplex/FileTransfer/Client.hs
+++ b/src/Simplex/FileTransfer/Client.hs
@@ -13,7 +13,7 @@ import Control.Monad
 import Control.Monad.Except
 import Crypto.Random (ChaChaDRG)
 import Data.Bifunctor (first)
-import qualified Data.ByteString.Builder as BB
+import Data.ByteString.Builder (Builder, byteString)
 import Data.ByteString.Char8 (ByteString)
 import qualified Data.ByteString.Char8 as B
 import Data.Int (Int64)
@@ -25,7 +25,6 @@ import qualified Network.HTTP2.Client as H
 import Simplex.FileTransfer.Description (mb)
 import Simplex.FileTransfer.Protocol
 import Simplex.FileTransfer.Transport
-import Simplex.Messaging.Builder (Builder, builder)
 import Simplex.Messaging.Client
   ( NetworkConfig (..),
     ProtocolClientError (..),
@@ -142,7 +141,7 @@ sendXFTPCommand c@XFTPClient {http2Client = HTTP2Client {sessionId}} pKey fId cm
       xftpEncodeTransmission sessionId (Just pKey) ("", fId, FileCmd (sFileParty @p) cmd)
   sendXFTPTransmission c t chunkSpec_
 
-sendXFTPTransmission :: XFTPClient -> Builder -> Maybe XFTPChunkSpec -> ExceptT XFTPClientError IO (FileResponse, HTTP2Body)
+sendXFTPTransmission :: XFTPClient -> ByteString -> Maybe XFTPChunkSpec -> ExceptT XFTPClientError IO (FileResponse, HTTP2Body)
 sendXFTPTransmission XFTPClient {config, http2Client = http2@HTTP2Client {sessionId}} t chunkSpec_ = do
   let req = H.requestStreaming N.methodPost "/" [] streamBody
       reqTimeout = (\XFTPChunkSpec {chunkSize} -> chunkTimeout config chunkSize) <$> chunkSpec_
@@ -156,9 +155,9 @@ sendXFTPTransmission XFTPClient {config, http2Client = http2@HTTP2Client {sessio
       _ -> pure (r, body)
     Left e -> throwError $ PCEResponseError e
   where
-    streamBody :: (BB.Builder -> IO ()) -> IO () -> IO ()
+    streamBody :: (Builder -> IO ()) -> IO () -> IO ()
     streamBody send done = do
-      send $ builder t
+      send $ byteString t
       forM_ chunkSpec_ $ \XFTPChunkSpec {filePath, chunkOffset, chunkSize} ->
         withFile filePath ReadMode $ \h -> do
           hSeek h AbsoluteSeek $ fromIntegral chunkOffset
diff --git a/src/Simplex/FileTransfer/Protocol.hs b/src/Simplex/FileTransfer/Protocol.hs
index 19d458107..578aefd15 100644
--- a/src/Simplex/FileTransfer/Protocol.hs
+++ b/src/Simplex/FileTransfer/Protocol.hs
@@ -24,7 +24,6 @@ import Data.List.NonEmpty (NonEmpty (..))
 import Data.Maybe (isNothing)
 import Data.Type.Equality
 import Data.Word (Word32)
-import Simplex.Messaging.Builder (Builder)
 import qualified Simplex.Messaging.Crypto as C
 import Simplex.Messaging.Encoding
 import Simplex.Messaging.Encoding.String
@@ -49,8 +48,7 @@ import Simplex.Messaging.Protocol
     encodeTransmission,
     messageTagP,
     tDecodeParseValidate,
-    tEncode,
-    tEncodeBatch,
+    tEncodeBatch1,
     tParse,
   )
 import Simplex.Messaging.Transport (SessionId, TransportError (..))
@@ -395,7 +393,7 @@ checkParty' c = case testEquality (sFileParty @p) (sFileParty @p') of
   Just Refl -> Just c
   _ -> Nothing
 
-xftpEncodeTransmission :: ProtocolEncoding e c => SessionId -> Maybe C.APrivateSignKey -> Transmission c -> Either TransportError Builder
+xftpEncodeTransmission :: ProtocolEncoding e c => SessionId -> Maybe C.APrivateSignKey -> Transmission c -> Either TransportError ByteString
 xftpEncodeTransmission sessionId pKey (corrId, fId, msg) = do
   let t = encodeTransmission currentXFTPVersion sessionId (corrId, fId, msg)
   xftpEncodeBatch1 $ signTransmission t
@@ -404,10 +402,8 @@ xftpEncodeTransmission sessionId pKey (corrId, fId, msg) = do
     signTransmission t = ((`C.sign` t) <$> pKey, t)
 
 -- this function uses batch syntax but puts only one transmission in the batch
-xftpEncodeBatch1 :: (Maybe C.ASignature, ByteString) -> Either TransportError Builder
-xftpEncodeBatch1 (sig, t) =
-  let t' = tEncodeBatch 1 . encodeLarge $ tEncode (sig, t)
-   in first (const TELargeMsg) $ C.pad' t' xftpBlockSize
+xftpEncodeBatch1 :: SentRawTransmission -> Either TransportError ByteString
+xftpEncodeBatch1 t = first (const TELargeMsg) $ C.pad (tEncodeBatch1 t) xftpBlockSize
 
 xftpDecodeTransmission :: ProtocolEncoding e c => SessionId -> ByteString -> Either XFTPErrorType (SignedTransmission e c)
 xftpDecodeTransmission sessionId t = do
diff --git a/src/Simplex/FileTransfer/Server.hs b/src/Simplex/FileTransfer/Server.hs
index c1fc4be41..f4b725462 100644
--- a/src/Simplex/FileTransfer/Server.hs
+++ b/src/Simplex/FileTransfer/Server.hs
@@ -18,6 +18,7 @@ import Control.Monad.Except
 import Control.Monad.Reader
 import Data.Bifunctor (first)
 import qualified Data.ByteString.Base64.URL as B64
+import Data.ByteString.Builder (byteString)
 import Data.ByteString.Char8 (ByteString)
 import qualified Data.ByteString.Char8 as B
 import Data.Functor (($>))
@@ -43,7 +44,6 @@ import Simplex.FileTransfer.Server.Stats
 import Simplex.FileTransfer.Server.Store
 import Simplex.FileTransfer.Server.StoreLog
 import Simplex.FileTransfer.Transport
-import Simplex.Messaging.Builder (builder)
 import qualified Simplex.Messaging.Crypto as C
 import qualified Simplex.Messaging.Crypto.Lazy as LC
 import Simplex.Messaging.Encoding.String
@@ -242,7 +242,7 @@ processRequest HTTP2Request {sessionId, reqBody = body@HTTP2Body {bodyHead}, sen
               send "padding error" -- TODO respond with BLOCK error?
               done
             Right t -> do
-              send $ builder t
+              send $ byteString t
               -- timeout sending file in the same way as receiving
               forM_ serverFile_ $ \ServerFile {filePath, fileSize, sbState} -> do
                 withFile filePath ReadMode $ \h -> sendEncFile h send sbState (fromIntegral fileSize)
diff --git a/src/Simplex/Messaging/Builder.hs b/src/Simplex/Messaging/Builder.hs
deleted file mode 100644
index 31e94bf7d..000000000
--- a/src/Simplex/Messaging/Builder.hs
+++ /dev/null
@@ -1,52 +0,0 @@
-{-# LANGUAGE StrictData #-}
-
-module Simplex.Messaging.Builder
-  ( Builder (length, builder),
-    byteString,
-    lazyByteString,
-    word16BE,
-    char8,
-    toLazyByteString,
-  )
-where
-
-import qualified Data.ByteString as B
-import qualified Data.ByteString.Builder as BB
-import qualified Data.ByteString.Lazy as LB
-import Data.Word (Word16)
-
-
--- length-aware builder
-data Builder = Builder {length :: Int, builder :: BB.Builder}
-
-instance Semigroup Builder where
-  Builder l1 b1 <> Builder l2 b2 = Builder (l1 + l2) (b1 <> b2)
-  {-# INLINE (<>) #-}
-
-instance Monoid Builder where
-  mempty = Builder 0 mempty
-  {-# INLINE mempty #-}
-  mconcat bs = Builder (sum ls) (mconcat bbs)
-    where
-      (ls, bbs) = foldr (\(Builder l b) ~(ls', bbs') -> (l : ls', b : bbs')) ([], []) bs
-  {-# INLINE mconcat #-}
-
-byteString :: B.ByteString -> Builder
-byteString s = Builder (B.length s) (BB.byteString s)
-{-# INLINE byteString #-}
-
-lazyByteString :: LB.ByteString -> Builder
-lazyByteString s = Builder (fromIntegral $ LB.length s) (BB.lazyByteString s)
-{-# INLINE lazyByteString #-}
-
-word16BE :: Word16 -> Builder
-word16BE = Builder 2 . BB.word16BE
-{-# INLINE word16BE #-}
-
-char8 :: Char -> Builder
-char8 = Builder 1 . BB.char8
-{-# INLINE char8 #-}
-
-toLazyByteString :: Builder -> LB.ByteString
-toLazyByteString = BB.toLazyByteString . builder
-{-# INLINE toLazyByteString #-}
diff --git a/src/Simplex/Messaging/Client.hs b/src/Simplex/Messaging/Client.hs
index 1d941ca08..3af07a657 100644
--- a/src/Simplex/Messaging/Client.hs
+++ b/src/Simplex/Messaging/Client.hs
@@ -96,10 +96,7 @@ import Data.Maybe (fromMaybe)
 import Data.Time.Clock (UTCTime, getCurrentTime)
 import Network.Socket (ServiceName)
 import Numeric.Natural
-import Simplex.Messaging.Builder (Builder)
-import qualified Simplex.Messaging.Builder as BB
 import qualified Simplex.Messaging.Crypto as C
-import Simplex.Messaging.Encoding
 import Simplex.Messaging.Encoding.String
 import Simplex.Messaging.Parsers (defaultJSON, dropPrefix, enumJSON)
 import Simplex.Messaging.Protocol
@@ -136,7 +133,7 @@ data PClient err msg = PClient
     pingErrorCount :: TVar Int,
     clientCorrId :: TVar Natural,
     sentCommands :: TMap CorrId (Request err msg),
-    sndQ :: TBQueue Builder,
+    sndQ :: TBQueue ByteString,
     rcvQ :: TBQueue (NonEmpty (SignedTransmission err msg)),
     msgQ :: Maybe (TBQueue (ServerTransmission msg))
   }
@@ -660,9 +657,11 @@ sendBatch c@ProtocolClient {client_ = PClient {sndQ}} b = do
     TBLargeTransmission Request {entityId} -> do
       putStrLn "send error: large message"
       pure [Response entityId $ Left $ PCETransportError TELargeMsg]
-    TBTransmissions s n rs -> do
-      when (n > 0) $ atomically $ writeTBQueue sndQ $ tEncodeBatch n s
-      mapConcurrently (getResponse c) rs
+    TBTransmissions s n rs
+      | n > 0 -> do
+          atomically $ writeTBQueue sndQ s
+          mapConcurrently (getResponse c) rs
+      | otherwise -> pure []
     TBTransmission s r -> do
       atomically $ writeTBQueue sndQ s
       (: []) <$> getResponse c r
@@ -675,11 +674,11 @@ sendProtocolCommand c@ProtocolClient {client_ = PClient {sndQ}, batch, blockSize
     -- two separate "atomically" needed to avoid blocking
     sendRecv :: SentRawTransmission -> Request err msg -> IO (Either (ProtocolClientError err) msg)
     sendRecv t r
-      | BB.length s > blockSize - 2 = pure $ Left $ PCETransportError TELargeMsg
+      | B.length s > blockSize - 2 = pure $ Left $ PCETransportError TELargeMsg
       | otherwise = atomically (writeTBQueue sndQ s) >> response <$> getResponse c r
       where
         s
-          | batch = tEncodeBatch 1 . encodeLarge $ tEncode t
+          | batch = tEncodeBatch1 t
           | otherwise = tEncode t
 
 -- TODO switch to timeout or TimeManager that supports Int64
diff --git a/src/Simplex/Messaging/Crypto.hs b/src/Simplex/Messaging/Crypto.hs
index d6a24f772..3564454ff 100644
--- a/src/Simplex/Messaging/Crypto.hs
+++ b/src/Simplex/Messaging/Crypto.hs
@@ -140,7 +140,6 @@ module Simplex.Messaging.Crypto
 
     -- * Message padding / un-padding
     pad,
-    pad',
     unPad,
 
     -- * X509 Certificates
@@ -206,8 +205,6 @@ import Database.SQLite.Simple.FromField (FromField (..))
 import Database.SQLite.Simple.ToField (ToField (..))
 import GHC.TypeLits (ErrorMessage (..), KnownNat, Nat, TypeError, natVal, type (+))
 import Network.Transport.Internal (decodeWord16, encodeWord16)
-import Simplex.Messaging.Builder (Builder, byteString, word16BE)
-import qualified Simplex.Messaging.Builder as BB
 import Simplex.Messaging.Encoding
 import Simplex.Messaging.Encoding.String
 import Simplex.Messaging.Parsers (blobFieldDecoder, parseAll, parseString)
@@ -922,14 +919,6 @@ pad msg paddedLen
     len = B.length msg
     padLen = paddedLen - len - 2
 
-pad' :: Builder -> Int -> Either CryptoError Builder
-pad' msg paddedLen
-  | len <= maxMsgLen && padLen >= 0 = Right $ word16BE (fromIntegral len) <> msg <> byteString (B.replicate padLen '#')
-  | otherwise = Left CryptoLargeMsgError
-  where
-    len = BB.length msg
-    padLen = paddedLen - len - 2
-
 unPad :: ByteString -> Either CryptoError ByteString
 unPad padded
   | B.length lenWrd == 2 && B.length rest >= len = Right $ B.take len rest
diff --git a/src/Simplex/Messaging/Encoding.hs b/src/Simplex/Messaging/Encoding.hs
index 846d071a1..6fa2c72c9 100644
--- a/src/Simplex/Messaging/Encoding.hs
+++ b/src/Simplex/Messaging/Encoding.hs
@@ -11,7 +11,6 @@ module Simplex.Messaging.Encoding
   ( Encoding (..),
     Tail (..),
     Large (..),
-    encodeLarge,
     _smpP,
     smpEncodeList,
     smpListP,
@@ -30,8 +29,6 @@ import qualified Data.List.NonEmpty as L
 import Data.Time.Clock.System (SystemTime (..))
 import Data.Word (Word16, Word32)
 import Network.Transport.Internal (decodeWord16, decodeWord32, encodeWord16, encodeWord32)
-import Simplex.Messaging.Builder (Builder, word16BE)
-import qualified Simplex.Messaging.Builder as BB
 import Simplex.Messaging.Parsers (parseAll)
 import Simplex.Messaging.Util ((<$?>))
 
@@ -141,10 +138,6 @@ instance Encoding Large where
     Large <$> A.take len
   {-# INLINE smpP #-}
 
-encodeLarge :: Builder -> Builder
-encodeLarge s = word16BE (fromIntegral $ BB.length s) <> s
-{-# INLINE encodeLarge #-}
-
 instance Encoding SystemTime where
   smpEncode = smpEncode . systemSeconds
   {-# INLINE smpEncode #-}
diff --git a/src/Simplex/Messaging/Notifications/Server.hs b/src/Simplex/Messaging/Notifications/Server.hs
index 302754bce..3e8c14607 100644
--- a/src/Simplex/Messaging/Notifications/Server.hs
+++ b/src/Simplex/Messaging/Notifications/Server.hs
@@ -369,7 +369,7 @@ receive th NtfServerClient {rcvQ, sndQ, rcvActiveAt} = forever $ do
 send :: Transport c => THandle c -> NtfServerClient -> IO ()
 send h@THandle {thVersion = v} NtfServerClient {sndQ, sessionId, sndActiveAt} = forever $ do
   t <- atomically $ readTBQueue sndQ
-  void . liftIO $ tPut h Nothing [(Nothing, encodeTransmission v sessionId t)]
+  void . liftIO $ tPut h [(Nothing, encodeTransmission v sessionId t)]
   atomically . writeTVar sndActiveAt =<< liftIO getSystemTime
 
 -- instance Show a => Show (TVar a) where
diff --git a/src/Simplex/Messaging/Protocol.hs b/src/Simplex/Messaging/Protocol.hs
index 539d6d348..f2571a9d4 100644
--- a/src/Simplex/Messaging/Protocol.hs
+++ b/src/Simplex/Messaging/Protocol.hs
@@ -144,7 +144,7 @@ module Simplex.Messaging.Protocol
     tParse,
     tDecodeParseValidate,
     tEncode,
-    tEncodeBatch,
+    tEncodeBatch1,
     batchTransmissions,
     batchTransmissions',
 
@@ -155,7 +155,6 @@ module Simplex.Messaging.Protocol
 where
 
 import Control.Applicative (optional, (<|>))
-import Control.Concurrent (threadDelay)
 import Control.Monad.Except
 import Data.Aeson (FromJSON (..), ToJSON (..))
 import qualified Data.Aeson.TH as J
@@ -163,8 +162,6 @@ import Data.Attoparsec.ByteString.Char8 (Parser, (<?>))
 import qualified Data.Attoparsec.ByteString.Char8 as A
 import Data.ByteString.Char8 (ByteString)
 import qualified Data.ByteString.Char8 as B
-import qualified Data.ByteString.Lazy.Char8 as LB
-import qualified Data.ByteString.Lazy.Internal as LB
 import Data.Char (isPrint, isSpace)
 import Data.Constraint (Dict (..))
 import Data.Functor (($>))
@@ -177,8 +174,6 @@ import Data.Time.Clock.System (SystemTime (..))
 import Data.Type.Equality
 import GHC.TypeLits (ErrorMessage (..), TypeError, type (+))
 import Network.Socket (HostName, ServiceName)
-import Simplex.Messaging.Builder (Builder, char8, lazyByteString)
-import qualified Simplex.Messaging.Builder as BB
 import qualified Simplex.Messaging.Crypto as C
 import Simplex.Messaging.Encoding
 import Simplex.Messaging.Encoding.String
@@ -1288,16 +1283,16 @@ instance Encoding CommandError where
       _ -> fail "bad command error type"
 
 -- | Send signed SMP transmission to TCP transport.
-tPut :: Transport c => THandle c -> Maybe Int -> NonEmpty SentRawTransmission -> IO [Either TransportError ()]
-tPut th delay_ = fmap concat . mapM tPutBatch . batchTransmissions (batch th) (blockSize th)
+tPut :: Transport c => THandle c -> NonEmpty SentRawTransmission -> IO [Either TransportError ()]
+tPut th = fmap concat . mapM tPutBatch . batchTransmissions (batch th) (blockSize th)
   where
     tPutBatch :: TransportBatch () -> IO [Either TransportError ()]
     tPutBatch = \case
       TBLargeTransmission _ -> [Left TELargeMsg] <$ putStrLn "tPut error: large message"
-      TBTransmissions s n _ -> replicate n <$> (tPutLog th (tEncodeBatch n s) <* mapM_ threadDelay delay_)
+      TBTransmissions s n _ -> replicate n <$> (tPutLog th s)
       TBTransmission s _ -> (: []) <$> tPutLog th s
 
-tPutLog :: Transport c => THandle c -> Builder -> IO (Either TransportError ())
+tPutLog :: Transport c => THandle c -> ByteString -> IO (Either TransportError ())
 tPutLog th s = do
   r <- tPutBlock th s
   case r of
@@ -1305,8 +1300,8 @@ tPutLog th s = do
     _ -> pure ()
   pure r
 
--- Builder in TBTransmissions does not include byte with transmissions count, it is added by tEncodeBatch
-data TransportBatch r = TBTransmissions Builder Int [r] | TBTransmission Builder r | TBLargeTransmission r
+-- ByteString in TBTransmissions includes byte with transmissions count
+data TransportBatch r = TBTransmissions ByteString Int [r] | TBTransmission ByteString r | TBLargeTransmission r
 
 batchTransmissions :: Bool -> Int -> NonEmpty SentRawTransmission -> [TransportBatch ()]
 batchTransmissions batch bSize = batchTransmissions' batch bSize . L.map (,())
@@ -1314,35 +1309,43 @@ batchTransmissions batch bSize = batchTransmissions' batch bSize . L.map (,())
 -- | encodes and batches transmissions into blocks,
 batchTransmissions' :: forall r. Bool -> Int -> NonEmpty (SentRawTransmission, r) -> [TransportBatch r]
 batchTransmissions' batch bSize
-  | batch = addBatch . foldr addTransmission ([], mempty, 0, [])
+  | batch = addBatch . foldr addTransmission ([], 0, 0, [], [])
   | otherwise = map mkBatch1 . L.toList
   where
     mkBatch1 :: (SentRawTransmission, r) -> TransportBatch r
     mkBatch1 (t, r)
       -- 2 bytes are reserved for pad size
-      | BB.length s <= bSize - 2 = TBTransmission s r
+      | B.length s <= bSize - 2 = TBTransmission s r
       | otherwise = TBLargeTransmission r
       where
         s = tEncode t
-    addTransmission :: (SentRawTransmission, r) -> ([TransportBatch r], Builder, Int, [r]) -> ([TransportBatch r], Builder, Int, [r])
-    addTransmission (t, r) acc@(bs, b, n, rs)
-      -- 3 = 2 bytes reserved for pad size + 1 for transmission count
-      | len + BB.length b <= bSize - 3 && n < 255 = (bs, s <> b, 1 + n, r : rs)
-      | len <= bSize - 3 = (addBatch acc, s, 1, [r])
-      | otherwise = (TBLargeTransmission r : addBatch acc, mempty, 0, [])
+    -- 3 = 2 bytes reserved for pad size + 1 for transmission count
+    bSize' = bSize - 3
+    addTransmission :: (SentRawTransmission, r) -> ([TransportBatch r], Int, Int, [ByteString], [r]) -> ([TransportBatch r], Int, Int, [ByteString], [r])
+    addTransmission (t, r) acc@(bs, len, n, ss, rs)
+      | len' <= bSize' && n < 255 = (bs, len', 1 + n, s : ss, r : rs)
+      | sLen <= bSize' = (addBatch acc, sLen, 1, [s], [r])
+      | otherwise = (TBLargeTransmission r : addBatch acc, 0, 0, [], [])
       where
-        s = encodeLarge $ tEncode t
-        len = BB.length s
-    addBatch :: ([TransportBatch r], Builder, Int, [r]) -> [TransportBatch r]
-    addBatch (bs, b, n, rs) = if n == 0 then bs else TBTransmissions b n rs : bs
+        s = tEncodeForBatch t
+        sLen = B.length s
+        len' = len + sLen
+    addBatch :: ([TransportBatch r], Int, Int, [ByteString], [r]) -> [TransportBatch r]
+    addBatch (bs, _len, n, ss, rs) = if n == 0 then bs else TBTransmissions b n rs : bs
+      where
+        b = B.concat $ B.singleton (lenEncode n) : ss
 
-tEncode :: SentRawTransmission -> Builder
-tEncode (sig, t) = lazyByteString $ LB.chunk (smpEncode $ C.signatureBytes sig) (LB.fromStrict t)
+tEncode :: SentRawTransmission -> ByteString
+tEncode (sig, t) = smpEncode (C.signatureBytes sig) <> t
 {-# INLINE tEncode #-}
 
-tEncodeBatch :: Int -> Builder -> Builder
-tEncodeBatch n s = char8 (lenEncode n) <> s
-{-# INLINE tEncodeBatch #-}
+tEncodeForBatch :: SentRawTransmission -> ByteString
+tEncodeForBatch = smpEncode . Large . tEncode
+{-# INLINE tEncodeForBatch #-}
+
+tEncodeBatch1 :: SentRawTransmission -> ByteString
+tEncodeBatch1 t = lenEncode 1 `B.cons` tEncodeForBatch t
+{-# INLINE tEncodeBatch1 #-}
 
 encodeTransmission :: ProtocolEncoding e c => Version -> ByteString -> Transmission c -> ByteString
 encodeTransmission v sessionId (CorrId corrId, queueId, command) =
diff --git a/src/Simplex/Messaging/Server.hs b/src/Simplex/Messaging/Server.hs
index d70dfe9ea..dea9b27c8 100644
--- a/src/Simplex/Messaging/Server.hs
+++ b/src/Simplex/Messaging/Server.hs
@@ -439,7 +439,7 @@ send h@THandle {thVersion = v} Client {sndQ, sessionId, sndActiveAt} = do
   labelMyThread . B.unpack $ "client $" <> encode sessionId <> " send"
   forever $ do
     ts <- atomically $ L.sortWith tOrder <$> readTBQueue sndQ
-    void . liftIO . tPut h Nothing $ L.map ((Nothing,) . encodeTransmission v sessionId) ts
+    void . liftIO . tPut h $ L.map ((Nothing,) . encodeTransmission v sessionId) ts
     atomically . writeTVar sndActiveAt =<< liftIO getSystemTime
   where
     tOrder :: Transmission BrokerMsg -> Int
diff --git a/src/Simplex/Messaging/Transport.hs b/src/Simplex/Messaging/Transport.hs
index 554b9a00a..c67c812af 100644
--- a/src/Simplex/Messaging/Transport.hs
+++ b/src/Simplex/Messaging/Transport.hs
@@ -78,7 +78,6 @@ import Network.Socket
 import qualified Network.TLS as T
 import qualified Network.TLS.Extra as TE
 import qualified Paths_simplexmq as SMQ
-import Simplex.Messaging.Builder (Builder, byteString, toLazyByteString)
 import qualified Simplex.Messaging.Crypto as C
 import Simplex.Messaging.Encoding
 import Simplex.Messaging.Parsers (dropPrefix, parse, parseRead1, sumTypeJSON)
@@ -135,9 +134,6 @@ class Transport c where
   -- | Write bytes to connection
   cPut :: c -> ByteString -> IO ()
 
-  -- | Write bytes to connection
-  cPut' :: c -> LB.ByteString -> IO ()
-
   -- | Receive ByteString from connection, allowing LF or CRLF termination.
   getLn :: c -> IO ByteString
 
@@ -221,11 +217,8 @@ instance Transport TLS where
     getBuffered tlsBuffer n t_ (T.recvData tlsContext)
 
   cPut :: TLS -> ByteString -> IO ()
-  cPut cxt = cPut' cxt . LB.fromStrict
-
-  cPut' :: TLS -> LB.ByteString -> IO ()
-  cPut' TLS {tlsContext, tlsTransportConfig = TransportConfig {transportTimeout = t_}} s =
-    withTimedErr t_ $ T.sendData tlsContext s
+  cPut TLS {tlsContext, tlsTransportConfig = TransportConfig {transportTimeout = t_}} =
+    withTimedErr t_ . T.sendData tlsContext . LB.fromStrict
 
   getLn :: TLS -> IO ByteString
   getLn TLS {tlsContext, tlsBuffer} = do
@@ -316,10 +309,10 @@ serializeTransportError = \case
   TEHandshake e -> "HANDSHAKE " <> bshow e
 
 -- | Pad and send block to SMP transport.
-tPutBlock :: Transport c => THandle c -> Builder -> IO (Either TransportError ())
+tPutBlock :: Transport c => THandle c -> ByteString -> IO (Either TransportError ())
 tPutBlock THandle {connection = c, blockSize} block =
-  bimapM (const $ pure TELargeMsg) (cPut' c . toLazyByteString) $
-    C.pad' block blockSize
+  bimapM (const $ pure TELargeMsg) (cPut c) $
+    C.pad block blockSize
 
 -- | Receive block from SMP transport.
 tGetBlock :: Transport c => THandle c -> IO (Either TransportError ByteString)
@@ -363,7 +356,7 @@ smpThHandle :: forall c. THandle c -> Version -> THandle c
 smpThHandle th v = (th :: THandle c) {thVersion = v, batch = v >= 4}
 
 sendHandshake :: (Transport c, Encoding smp) => THandle c -> smp -> ExceptT TransportError IO ()
-sendHandshake th = ExceptT . tPutBlock th . byteString . smpEncode
+sendHandshake th = ExceptT . tPutBlock th . smpEncode
 
 getHandshake :: (Transport c, Encoding smp) => THandle c -> ExceptT TransportError IO smp
 getHandshake th = ExceptT $ (parse smpP (TEHandshake PARSE) =<<) <$> tGetBlock th
diff --git a/src/Simplex/Messaging/Transport/WebSockets.hs b/src/Simplex/Messaging/Transport/WebSockets.hs
index 486ae1f20..4a39234b5 100644
--- a/src/Simplex/Messaging/Transport/WebSockets.hs
+++ b/src/Simplex/Messaging/Transport/WebSockets.hs
@@ -72,9 +72,6 @@ instance Transport WS where
   cPut :: WS -> ByteString -> IO ()
   cPut = sendBinaryData . wsConnection
 
-  cPut' :: WS -> LB.ByteString -> IO ()
-  cPut' = sendBinaryData . wsConnection
-
   getLn :: WS -> IO ByteString
   getLn c = do
     s <- trimCR <$> receiveData (wsConnection c)
diff --git a/tests/CoreTests/BatchingTests.hs b/tests/CoreTests/BatchingTests.hs
index c21ec8c7a..bf31f0811 100644
--- a/tests/CoreTests/BatchingTests.hs
+++ b/tests/CoreTests/BatchingTests.hs
@@ -5,9 +5,8 @@ module CoreTests.BatchingTests (batchingTests) where
 import Control.Concurrent.STM
 import Control.Monad
 import Data.ByteString.Char8 (ByteString)
+import qualified Data.ByteString as B
 import qualified Data.List.NonEmpty as L
-import Simplex.Messaging.Builder (Builder)
-import qualified Simplex.Messaging.Builder as BB
 import Simplex.Messaging.Client
 import qualified Simplex.Messaging.Crypto as C
 import Simplex.Messaging.Protocol
@@ -170,8 +169,8 @@ randomSENDCmd c len = do
   msg <- atomically $ C.randomBytes len g
   mkTransmission c (Just rpKey, sId, Cmd SSender $ SEND noMsgFlags msg)
 
-lenOk :: Builder -> Bool
-lenOk s = 0 < BB.length s && BB.length s <= smpBlockSize - 2
+lenOk :: ByteString -> Bool
+lenOk s = 0 < B.length s && B.length s <= smpBlockSize - 2
 
 lenOk1 :: TransportBatch r -> Bool
 lenOk1 = \case
diff --git a/tests/NtfClient.hs b/tests/NtfClient.hs
index 49b68a57c..c75181ba4 100644
--- a/tests/NtfClient.hs
+++ b/tests/NtfClient.hs
@@ -136,7 +136,7 @@ ntfServerTest _ t = runNtfTest $ \h -> tPut' h t >> tGet' h
     tPut' :: THandle c -> (Maybe C.ASignature, ByteString, ByteString, smp) -> IO ()
     tPut' h@THandle {sessionId} (sig, corrId, queueId, smp) = do
       let t' = smpEncode (sessionId, corrId, queueId, smp)
-      [Right ()] <- tPut h Nothing [(sig, t')]
+      [Right ()] <- tPut h [(sig, t')]
       pure ()
     tGet' h = do
       [(Nothing, _, (CorrId corrId, qId, Right cmd))] <- tGet h
diff --git a/tests/SMPClient.hs b/tests/SMPClient.hs
index b75b1dbe9..32fb312a2 100644
--- a/tests/SMPClient.hs
+++ b/tests/SMPClient.hs
@@ -164,7 +164,7 @@ smpServerTest _ t = runSmpTest $ \h -> tPut' h t >> tGet' h
     tPut' :: THandle c -> (Maybe C.ASignature, ByteString, ByteString, smp) -> IO ()
     tPut' h@THandle {sessionId} (sig, corrId, queueId, smp) = do
       let t' = smpEncode (sessionId, corrId, queueId, smp)
-      [Right ()] <- tPut h Nothing [(sig, t')]
+      [Right ()] <- tPut h [(sig, t')]
       pure ()
     tGet' h = do
       [(Nothing, _, (CorrId corrId, qId, Right cmd))] <- tGet h
diff --git a/tests/ServerTests.hs b/tests/ServerTests.hs
index 1097833d4..4bd468f16 100644
--- a/tests/ServerTests.hs
+++ b/tests/ServerTests.hs
@@ -89,7 +89,7 @@ signSendRecv h@THandle {thVersion, sessionId} pk (corrId, qId, cmd) = do
 
 tPut1 :: Transport c => THandle c -> SentRawTransmission -> IO (Either TransportError ())
 tPut1 h t = do
-  [r] <- tPut h Nothing [t]
+  [r] <- tPut h [t]
   pure r
 
 tGet1 :: (ProtocolEncoding err cmd, Transport c, MonadIO m, MonadFail m) => THandle c -> m (SignedTransmission err cmd)