diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 6ecdd88815..9ccb4226be 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -383,13 +383,21 @@ jobs:
         if: ${{ matrix.job.postgres-version }}
         # 1. Mount postgres data files onto a tmpfs in-memory filesystem to reduce overhead of docker's overlayfs layer.
         # 2. Expose the unix socket for postgres. This removes latency of using docker-proxy for connections.
+        # 3. We disable crash-safety features for speed: fsync, synchronous commits, full-page writes.
+        #    Note: synchronous commits are enabled/disabled at runtime by Synapse, so there is also
+        #    code in `tests/server.py` to configure this as off.
         run: |
           docker run -d -p 5432:5432 \
-            --tmpfs /var/lib/postgres:rw,size=6144m \
+            --tmpfs /var/lib/postgresql:rw,size=6144m \
             --mount 'type=bind,src=/var/run/postgresql,dst=/var/run/postgresql' \
             -e POSTGRES_PASSWORD=postgres \
             -e POSTGRES_INITDB_ARGS="--lc-collate C --lc-ctype C --encoding UTF8" \
-            postgres:${{ matrix.job.postgres-version }}
+            postgres:${{ matrix.job.postgres-version }} \
+              -c fsync=off \
+              -c synchronous_commit=off \
+              -c full_page_writes=off \
+              -c wal_level=minimal \
+              -c max_wal_senders=0
 
       - name: Install Rust
         uses: dtolnay/rust-toolchain@e97e2d8cc328f1b50210efc529dca0028893a2d9 # master
diff --git a/docker/complement/conf/postgres.supervisord.conf b/docker/complement/conf/postgres.supervisord.conf
index 657845dfdb..e48921236f 100644
--- a/docker/complement/conf/postgres.supervisord.conf
+++ b/docker/complement/conf/postgres.supervisord.conf
@@ -1,5 +1,11 @@
 [program:postgres]
+# Disable crash-safety features for speed: fsync, synchronous commit, full page writes
 command=/usr/local/bin/prefix-log gosu postgres postgres
+    -c fsync=off
+    -c synchronous_commit=off
+    -c full_page_writes=off
+    -c wal_level=minimal
+    -c max_wal_senders=0
 
 # Only start if START_POSTGRES=true
 autostart=%(ENV_START_POSTGRES)s