I just created bug 660577 which consolidated five bug reports, all of which were complaining about Firefox 4 having high memory usage and/or OOM aborts on image-heavy pages. This is a clear regression from Firefox 3.6, and appears to have two likely causes:
- The introduction of infallible new/new[] means Firefox 4 sometimes aborts where Firefox 3.6 would try to recover. (Kyle Huey already opened bug 660580 to fix this. Thanks, Kyle!)
- image.mem.min_discard_timeout_ms was increased from 10,000 (10 seconds) to 120,000 (120 seconds). This means that Firefox holds on to some image data (I don’t understand the exact details) for longer.
Input from people who know the details of this stuff would be most welcome! Thanks.