diff --git a/tests/mw-dev/README.md b/tests/mw-dev/README.md
index 94ed9cd6..62397f01 100644
--- a/tests/mw-dev/README.md
+++ b/tests/mw-dev/README.md
@@ -839,6 +839,12 @@ The former `posthog_frozen_perf_trino_cached` selection has been removed; use
 `posthog_frozen_perf` instead. Omit the workflow's `duckgres_image` override so the
 control-plane build explicitly persists the expected baseline cache setting.
 
+This experimental branch enables `optimizer.dictionary-aggregation=true` in
+the isolated Trino coordinator and worker configurations. The shared fixture
+template also applies this setting to isolated Trino E2E clusters. Production
+configuration is managed separately. For an off/on benchmark, use the same
+digest-pinned Trino image and the full query corpus in both runs.
+
 For local invocation, set `SCENARIO_NAME=posthog_frozen_perf` and `E2E_SUITE=trino`
 before both `tests/mw-dev/run.sh deploy` and `test-scenario`. Use the existing lane
 credentials, images, and namespace requirements. The harness starts three Trino
diff --git a/tests/mw-dev/manifests.trino.tmpl.yaml b/tests/mw-dev/manifests.trino.tmpl.yaml
index 31d73d72..d3513c25 100644
--- a/tests/mw-dev/manifests.trino.tmpl.yaml
+++ b/tests/mw-dev/manifests.trino.tmpl.yaml
@@ -108,6 +108,7 @@ data:
     cache-manager.name=memory
   config.properties: |
     coordinator=true
+    optimizer.dictionary-aggregation=true
     node-scheduler.include-coordinator=false
     http-server.http.port=8080
     http-server.https.enabled=true
@@ -174,6 +175,7 @@ data:
     cache-manager.name=memory
   config.properties: |
     coordinator=false
+    optimizer.dictionary-aggregation=true
     http-server.http.port=8080
     discovery.uri=http://duckgres-trino.${NAMESPACE}.svc:8080
     query.max-memory=${TRINO_QUERY_MEMORY}
diff --git a/tests/mw-dev/run_sh_test.go b/tests/mw-dev/run_sh_test.go
index 7a2a958d..fed397c8 100644
--- a/tests/mw-dev/run_sh_test.go
+++ b/tests/mw-dev/run_sh_test.go
@@ -227,7 +227,7 @@ func TestTrinoWorkersMatchDuckgresAggregateCompute(t *testing.T) {
 		}
 		data := manifest["data"].(map[string]any)
 		config := data["config.properties"].(string)
-		for _, want := range []string{"query.max-memory=6GB", "query.max-memory-per-node=" + expectedPerNode} {
+		for _, want := range []string{"query.max-memory=6GB", "query.max-memory-per-node=" + expectedPerNode, "optimizer.dictionary-aggregation=true"} {
 			if !strings.Contains(config, want) {
 				t.Errorf("Trino %s config missing %q:\n%s", name, want, config)
 			}