diff --git a/docker/docker-compose.yaml b/docker/docker-compose.yaml
index 1f8f0f0..0089d7c 100644
--- a/docker/docker-compose.yaml
+++ b/docker/docker-compose.yaml
@@ -59,6 +59,7 @@ services:
     entrypoint: ["nitro"]
     command:
       - --conf.file=/config/l3-nodeConfig.json
+      - --execution.sequencer.max-block-speed=250ms
       - --node.dangerous.disable-blob-reader
       - --http.addr=0.0.0.0
       - --http.port=8547
diff --git a/docker/testnode-entrypoint.sh b/docker/testnode-entrypoint.sh
index fc67d87..61f32ad 100644
--- a/docker/testnode-entrypoint.sh
+++ b/docker/testnode-entrypoint.sh
@@ -137,6 +137,7 @@ if [ "$VARIANT" != "l2" ]; then
 	start_background env HOME="$DATA_ROOT/l3node" /usr/local/bin/nitro \
 		--validation.wasm.allowed-wasm-module-roots "$NITRO_WASM_ROOTS" \
 		--conf.file="$CONFIG_ROOT/l3-nodeConfig.json" \
+		--execution.sequencer.max-block-speed=250ms \
 		--node.dangerous.disable-blob-reader \
 		--node.bold.check-staker-switch-interval=1s \
 		--node.staker.dangerous.without-block-validator \
diff --git a/packages/core/src/node-config-patches.ts b/packages/core/src/node-config-patches.ts
index 35ff67c..e987fcd 100644
--- a/packages/core/src/node-config-patches.ts
+++ b/packages/core/src/node-config-patches.ts
@@ -25,6 +25,14 @@ const FAST_EXECUTION_SEQUENCER_CONFIG = {
 	"max-block-speed": "100ms",
 } as const;
 
+// L3 sequencer runs at 250ms (not 100ms) to widen the gap between block
+// production cycles, reducing the consensus/execution msgIdx-race window that
+// under load makes the TransactionStreamer reject eth_sendRawTransaction with
+// "wrong msgIdx" (JSON-RPC -32000).
+const L3_EXECUTION_SEQUENCER_CONFIG = {
+	"max-block-speed": "250ms",
+} as const;
+
 function getJsonObject(parent: JsonObject, key: string): JsonObject {
 	const value = parent[key];
 	if (typeof value !== "object" || value === null || Array.isArray(value)) {
@@ -146,7 +154,7 @@ export function patchGeneratedL3NodeConfig(
 	dangerous["disable-blob-reader"] = true;
 	delayedSequencer["finalize-distance"] = 0;
 	execution["forwarding-target"] = "null";
-	Object.assign(getOrCreateJsonObject(execution, "sequencer"), FAST_EXECUTION_SEQUENCER_CONFIG);
+	Object.assign(getOrCreateJsonObject(execution, "sequencer"), L3_EXECUTION_SEQUENCER_CONFIG);
 	next["persistent"] = { chain: "local" };
 	next["ws"] = { addr: "0.0.0.0" };
 
diff --git a/packages/core/test/node-config-patches.test.ts b/packages/core/test/node-config-patches.test.ts
index 0853771..44c9439 100644
--- a/packages/core/test/node-config-patches.test.ts
+++ b/packages/core/test/node-config-patches.test.ts
@@ -185,7 +185,7 @@ describe("patchGeneratedL3NodeConfig", () => {
 		expect(result.execution).toEqual({
 			"forwarding-target": "null",
 			sequencer: {
-				"max-block-speed": "100ms",
+				"max-block-speed": "250ms",
 			},
 		});
 		expect(result.persistent).toEqual({ chain: "local" });