diff --git a/programs/test_slow_decompression.c b/programs/test_slow_decompression.c
index f6a8d13..f691960 100644
--- a/programs/test_slow_decompression.c
+++ b/programs/test_slow_decompression.c
@@ -432,6 +432,8 @@ tmain(int argc, tchar *argv[])
 
 	program_invocation_name = get_filename(argv[0]);
 
+	begin_performance_test();
+
 	/* static huffman case */
 	generate_empty_static_huffman_blocks(in, sizeof(in));
 	t = do_test_libdeflate("static huffman", in, sizeof(in),
@@ -457,7 +459,7 @@ tmain(int argc, tchar *argv[])
 	 * FIXME: make it faster.
 	 */
 	putchar('\n');
-	ASSERT(t < 5 * tz);
+	ASSERT(t < 4 * tz);
 
 	/* original reproducer */
 	t = do_test_libdeflate("original repro", orig_repro, sizeof(orig_repro),
diff --git a/programs/test_util.c b/programs/test_util.c
index 3a69235..63eb536 100644
--- a/programs/test_util.c
+++ b/programs/test_util.c
@@ -59,6 +59,16 @@ assertion_failed(const char *expr, const char *file, int line)
 	abort();
 }
 
+void
+begin_performance_test(void)
+{
+	if (getenv("INCLUDE_PERF_TESTS") == NULL) {
+		printf("Skipping '%"TS"' since it's a performance test, which may be flaky.\n",
+		       program_invocation_name);
+		exit(0);
+	}
+}
+
 static size_t
 get_page_size(void)
 {
diff --git a/programs/test_util.h b/programs/test_util.h
index dcb5ac3..10f025a 100644
--- a/programs/test_util.h
+++ b/programs/test_util.h
@@ -44,6 +44,8 @@ assertion_failed(const char *expr, const char *file, int line);
 #define ASSERT(expr) { if (unlikely(!(expr))) \
 	assertion_failed(#expr, __FILE__, __LINE__); }
 
+extern void begin_performance_test(void);
+
 extern void alloc_guarded_buffer(size_t size, u8 **start_ret, u8 **end_ret);
 extern void free_guarded_buffer(u8 *start, u8 *end);