diff --git a/test_runner/regress/test_pg_regress.py b/test_runner/regress/test_pg_regress.py
index 411888efb..cb32c9fcc 100644
--- a/test_runner/regress/test_pg_regress.py
+++ b/test_runner/regress/test_pg_regress.py
@@ -20,6 +20,9 @@ from fixtures.pg_version import PgVersion
 from fixtures.remote_storage import s3_storage
 from fixtures.utils import skip_in_debug_build
 
+import time
+import threading
+
 if TYPE_CHECKING:
     from fixtures.neon_fixtures import PgBin
     from pytest import CaptureFixture
@@ -156,6 +159,23 @@ def test_pg_regress(
     )
     endpoint.safe_psql(f"CREATE DATABASE {DBNAME}")
 
+    def run_confplay(connstr):
+        log.info("Starting configuration changer")
+        sizes = [1, 0]
+        i = 0
+        t = threading.currentThread()
+        while getattr(t, "run", True):
+            size = sizes[i % len(sizes)]
+            i += 1
+            pg_bin.run(["psql", "-c", f"ALTER SYSTEM SET neon.file_cache_size_limit='{size}MB'" , connstr])
+            pg_bin.run(["psql", "-c", f"SELECT pg_reload_conf()" , connstr])
+            time.sleep(0.2)
+        log.info("Finishing configuration changer")
+
+    connstr = endpoint.connstr()
+    thread = threading.Thread(target=run_confplay, args=(connstr,), daemon=True)
+    thread.start()
+
     # Create some local directories for pg_regress to run in.
     runpath = test_output_dir / "regress"
     (runpath / "testtablespace").mkdir(parents=True)
@@ -189,7 +209,8 @@ def test_pg_regress(
     with capsys.disabled():
         pg_bin.run(pg_regress_command, env=env_vars, cwd=runpath)
 
-    post_checks(env, test_output_dir, DBNAME, endpoint)
+    thread.run = False
+    time.sleep(1)
 
 
 # Run the PostgreSQL "isolation" tests, in src/test/isolation.