A dramatic reduction in performance (especially tab switching performance) is experienced on when hardware acceleration is enabled in the settings menu. System info: Laptop - Win7x64Pro - Core i7-372QM - Mem: 16GB - Storage: RAID0 Intel 330 SSDs with 750MB/sec sustained read. In other words, this is a screaming fast laptop. I've disabled a variety of plugins such as FireBug. These don't make much of a difference. The only thing that changes tab switching performance noticeably it is disabling hardware acceleration. Found this solution here: http://support.mozilla.org/en-US/questions/787024 : "Discovered that disabling hardware acceleration resolved all the remaining issues..." This is a massive performance hit. I suspect that this has been the same issue across all my PCs (some laptops, some desktops, some gaming desktops, some integrated graphics, some dedicated graphics, various addons enabled, various versions of FF installed... all fast computers with high RAM and screaming fast SSDs and they have all been experiencing slow tab switching, especially after getting 10+ tabs open, but even with just two open).