Not an insider, just a community member who reads a lot of bugs:-). Windows builds are done on MSVC 2005 with profile guided optimization enabled. Mac and Linux builds are done with GCC 4.2 also with PGO enabled. No clue about AMD CPUs, though, sorry. First I've ever heard of someone having problems like that.
There's a lot of work underway now to improve cycle collection times, which is where many of the pauses come from. Also, work is underway for both Generational and Incremental GC, which should improve things on the GC side. At least with a rapid release schedule, those improvements will ship when they're ready rather than waiting for other things to finish up first like they would have in the past.
bz pointed out elsewhere in this thread that while ESR releases will get critical security updates backported to them, they won't be receiving any major architectural updates/refactorings that inherently improve security. So in that respect, ESR releases will be more limited security-wise than the mainline release.
You'll be happy to hear that Asa isn't the only decision maker at Mozilla, nor is his opinion held at any higher esteem than anyone else's there. Nice troll, though.