User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0) Gecko/20100101 Firefox/4.0 Build Identifier: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0) Gecko/20100101 Firefox/4.0 When reading the following, keep in mind that all these things were handled well in the latest Firefox 3. When the memory usage hits around 3GB, Firefox stops responding. I usually have 20-30 tabs open and leave the application open for days (often weeks) at a time. When Firefox is started and pages have loaded, usage is 500-750MB. This slowly increases over time (while idling, no new pages are being loaded) until the 3GB ceiling is reached at which point Firefox freezes. For me, this seems to take less than 24 hours. In Firefox 3, with the same set of pages, the "leak" didn't happen. Reproducible: Always My main complaint is that something that didn't lead to a freeze or crash in FF3 now does in FF4.

This is the usual me to, Win XP, 2 different machines, 2 and 3 GB of physical RAM. It happens all the time. I used to have arround 20 tabs open and keep FF3 open a week or longer before. With FF4 the memory usage raises from initial 400 MB to 1GB within 2-3 hours. At this stage FF4 is hardly usable, since nearly every action (putting the mouse over a link and waiting for the link to change colour or typing a single letter, waiting for the letter to apear) is preceeded by 3-5 seconds of heavy CPU (100% one core) usage. For me this feels like garbage collection gone mad. I wonder how FF4 can be useful this way on a mobile or even a netbook. To do my business I had to revert to FF3.6.16. I have to confess, I have quite a few addons, I even deinstalled some of them (including the Developer Toolbar thing), but I mean a naked FF4 without any plugin (especially NoScript, AdBlock Plus, FireBug and Greasemonkey) is hardly competitive any more.

(In reply to comment #1) > I have to confess, I have quite a few addons, I even deinstalled some of them > (including the Developer Toolbar thing), but I mean a naked FF4 without any > plugin (especially NoScript, AdBlock Plus, FireBug and Greasemonkey) is hardly > competitive any more. It's not about having to run Fx forever extension-less, but rather pinpointing the Cause. Maybe it's an Extension Cause, maybe an Extension is exposing some Fx/Core Bug. Just plain saying Fx is consuming X MB RAM in Y Hours and is unusable is a nice Description of a Symptom, but doesn't help/isn't sufficient to track down the Cause :-/.

(In reply to comment #1) I'm not sure this is the same issue. My experience is that FF becomes completely unresponsive. There is no CPU or I/O use once it's reached the 3GB limit and frozen. After trying to elicit any kind of response, Windows pops up saying the application is unresponsive and asks if you want to close it. After allowing this, FF's crash reporter comes up (as expected when Windows force closes FF). I haven't experienced FF4 becoming laggy as you describe. But I guess this could be attributed to the difference between behaviors on XP vs Win7. (In reply to comment #2) Any "me too" responses are helpful so long as they include a description of the environment and experience with the issue. They help narrow down possible causes. Commenting on the helpfulness of other comments is unhelpful.

I've closed some tabs that I suspect may be invoking this issue in that they lack a relatively professional polish. Memory use has been holding around 1.6GB (virtual) for the last day and a half. I suspect that that FF4 is not handling some poorly written Javascript as well as FF3 did. I suppose it also could be some sort of interaction between ABP and the sites I chose to close. I turns out I have 40 tabs remaining open. I underestimated how many tabs I had previously. The count before was 49-50.

> It's not about having to run Fx forever extension-less, but rather pinpointing > the Cause. Maybe it's an Extension Cause, maybe an Extension is exposing some > Fx/Core Bug. > Just plain saying Fx is consuming X MB RAM in Y Hours and is unusable is a nice > Description of a Symptom, but doesn't help/isn't sufficient to track down the > Cause :-/. I understand this and I appreciate this, since was trying to report this since beta-10 and found that I do not know how to provide more useful information to the project. My desperate attempt right now was to find "leak" in the bugzilla and jump on the case which sounded most similar. For example I could also have reported, that FF3.6.15 was a improvement over 3.6.13 in my setting, so the 3.5 were close to perfect in the end, the 3.6.X became worse over time, till 3.6.15. But there is also lots of coevolution going on in terms of add ons ... I'd like to help, my time is limited, but any suggestions, what to try, where to look, what to measure?

Reporter, please try safe mode: http://support.mozilla.com/kb/Safe+Mode ...and if that works fine, enable addons a few at a time until the culprit is found. Frank, there are lots of potential causes of high memory usage ranging from incompatible addons, to bugs in Firefox, to broken JS (see meta bug 640452 and dependancies for a start). Without specific steps, there's no reason to think that one case of high memory usage is the same as any other. Best bet is to start your own bug and add as much info as you can to that. Thanks!

(In reply to comment #6) > Reporter, please try safe mode: > http://support.mozilla.com/kb/Safe+Mode > ...and if that works fine, enable addons a few at a time until the culprit is > found. I loaded those pages that I think might be encouraging this issue and restarted FF in safe mode. It's only been going for about 30 minutes and during that time, usage has steadily risen by about 175MB in that time. It'll be at least another 7 hours before it reaches 3GB though.

(In reply to comment #7) > I loaded those pages that I think might be encouraging this issue and restarted > FF in safe mode. It's only been going for about 30 minutes and during that > time, usage has steadily risen by about 175MB in that time. It'll be at least > another 7 hours before it reaches 3GB though. Okay, so this seems to be normal behavior. Time to figure out which add-on it is.

Seems to be Ghostery 2.5.2.

Thanks for the update. Marking this as invalid, since not a bug with Firefox. Please contact the author of the addon linking them back to this bug / requesting a fix. Thanks!