diff --git a/test_runner/regress/test_lfc_working_set_approximation.py b/test_runner/regress/test_lfc_working_set_approximation.py
index e422622167..a28bc3d047 100644
--- a/test_runner/regress/test_lfc_working_set_approximation.py
+++ b/test_runner/regress/test_lfc_working_set_approximation.py
@@ -22,7 +22,12 @@ def test_lfc_working_set_approximation(neon_simple_env: NeonEnv):
     log.info("Creating endpoint with 1MB shared_buffers and 64 MB LFC")
     endpoint = env.endpoints.create_start(
         "main",
-        config_lines=["neon.max_file_cache_size='128MB'", "neon.file_cache_size_limit='64MB'"],
+        config_lines=[
+            "autovacuum=off",
+            "bgwriter_lru_maxpages=0",
+            "neon.max_file_cache_size='128MB'",
+            "neon.file_cache_size_limit='64MB'",
+        ],
     )
 
     cur = endpoint.connect().cursor()
@@ -72,7 +77,7 @@ WITH (fillfactor='100');
     # verify working set size after some index access of a few select pages only
     blocks = query_scalar(cur, "select approximate_working_set_size(true)")
     log.info(f"working set size after some index access of a few select pages only {blocks}")
-    assert blocks < 12
+    assert blocks < 20
 
 
 @pytest.mark.skipif(not USE_LFC, reason="LFC is disabled, skipping")
@@ -83,6 +88,7 @@ def test_sliding_working_set_approximation(neon_simple_env: NeonEnv):
         branch_name="main",
         config_lines=[
             "autovacuum = off",
+            "bgwriter_lru_maxpages=0",
             "shared_buffers=1MB",
             "neon.max_file_cache_size=256MB",
             "neon.file_cache_size_limit=245MB",
@@ -92,9 +98,9 @@ def test_sliding_working_set_approximation(neon_simple_env: NeonEnv):
     cur = conn.cursor()
     cur.execute("create extension neon")
     cur.execute(
-        "create table t(pk integer primary key, count integer default 0, payload text default repeat('?', 128))"
+        "create table t(pk integer primary key, count integer default 0, payload text default repeat('?', 1000)) with (fillfactor=10)"
     )
-    cur.execute("insert into t (pk) values (generate_series(1,1000000))")
+    cur.execute("insert into t (pk) values (generate_series(1,100000))")
     time.sleep(2)
     before_10k = time.monotonic()
     cur.execute("select sum(count) from t where pk between 10000 and 20000")
@@ -115,5 +121,5 @@ def test_sliding_working_set_approximation(neon_simple_env: NeonEnv):
     size = cur.fetchall()[0][0] // 8192
     log.info(f"Table size {size} blocks")
 
-    assert estimation_1k >= 20 and estimation_1k <= 40
-    assert estimation_10k >= 200 and estimation_10k <= 440
+    assert estimation_1k >= 900 and estimation_1k <= 2000
+    assert estimation_10k >= 9000 and estimation_10k <= 20000