diff -r 0271bd4aba8d dom/base/nsJSEnvironment.cpp
--- a/dom/base/nsJSEnvironment.cpp	Sat Sep 19 16:18:34 2009 +0300
+++ b/dom/base/nsJSEnvironment.cpp	Sat Sep 19 19:50:57 2009 +0300
@@ -3586,7 +3586,7 @@ nsJSContext::MaybeCC(PRBool aHigherProba
       (sDelayedCCollectCount > NS_MAX_DELAYED_CCOLLECT) &&
       ((sCCSuspectChanges > NS_MIN_SUSPECT_CHANGES &&
         GetGCRunsSinceLastCC() > NS_MAX_GC_COUNT) ||
-       (sCCSuspectChanges > NS_MAX_SUSPECT_CHANGES))) {
+       (sCCSuspectChanges > NS_MAX_SUSPECT_CHANGES) || !sUserIsActive)) {
     if ((PR_Now() - sPreviousCCTime) >=
         PRTime(NS_MIN_CC_INTERVAL * PR_USEC_PER_MSEC)) {
       nsJSContext::CC();