We've identified a bug that may cause, under certain circumstances, periodic freezes of the Firefox UI, in terms of a short freeze every about 9 minutes. This only affects a small amount of users, so, if you don't notice this behavior, you can stop reading.
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As part of the Memshrink effort, we reduced the SQLite page cache used by Places. This is not a leak, the page cache is actively used by SQLite to improve performances by reducing disk I/O. Originally Places was allowed to use a large cache (maximum 6% of physical memory, per connection), to ensure responsiveness of the awesome bar.
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