User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:2.0b12pre) Gecko/20110203 Firefox/4.0b12pre Build Identifier: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:2.0b12pre) Gecko/20110203 Firefox/4.0b12pre I recently replaced Firefox-3.6.13 (32-bit) with Minefield-4.0b12pre. 3.6.13 used 80-100MB RAM, 4.0b12 uses 100MB when first open and quickly builds to 300MB (375MB when first used after suspend). Note both versions are used with the same set of bookmarks, open tabs, etc Reproducible: Always Steps to Reproduce: 1. Start 4.0b12pre and watch the RAM used build 2. 3. Actual Results: Currently at 300MB with 4 tabs open, none of which have flash, videos, etc. Exited and restarted (saving tabs to reopen at start-up) and now at 99MB. A few minutes later and already at 122MB without doing anything. Expected Results: RAM used to stay constant if I do not open any more tabs

bug 631494 is titled "Massive memory leak with Adblock Plus 1.3.3 installed". I do not have Adblock Plus 1.3.3 installed, so I don't believe this is a duplicate of bug 631949