How is that possible, I get FF crashes literally every time I load a moderately intensive website (eg. Google Keep). I still use FF because I can't abide Chrome. My PC is admittedly a bit older (only 6 gigs RAM) but still.
I've got 99 problems with Firefox, but a crash ain't one.
What doesn't work is trying to compile the browser on the Pi. The build process has some really gigantic source files that cause the compiler to choke.
The crashes could be some addon or other profile feature interfering with Firefox's stability. I had a profile that I migrated from FF 1.x, and I finally had to put that one to rest...
Firefox should literally never crash. If it does, that's a serious bug (but especially on Windows, not necessarily in Firefox itself).