--- a/testing/profiles/prefs_general.js
+++ b/testing/profiles/prefs_general.js
@@ -40,16 +40,18 @@ user_pref("network.manage-offline-status
 user_pref("network.http.speculative-parallel-limit", 0);
 user_pref("dom.min_background_timeout_value", 1000);
 user_pref("test.mousescroll", true);
 user_pref("security.default_personal_cert", "Select Automatically"); // Need to client auth test be w/o any dialogs
 user_pref("network.http.prompt-temp-redirect", false);
 user_pref("media.preload.default", 2); // default = metadata
 user_pref("media.preload.auto", 3); // auto = enough
 user_pref("media.cache_size", 1000);
+user_pref("media.memory_cache_max_size", 32);
+user_pref("media.memory_caches_combined_limit_kb", 256);
 user_pref("media.volume_scale", "0.01");
 user_pref("media.test.dumpDebugInfo", true);
 user_pref("media.dormant-on-pause-timeout-ms", 0); // Enter dormant immediately without waiting for timeout.
 user_pref("media.suspend-bkgnd-video.enabled", false);
 user_pref("security.warn_viewing_mixed", false);
 user_pref("app.update.enabled", false);
 user_pref("app.update.staging.enabled", false);
 user_pref("app.update.url.android", "");