I'm using Google Chrome and it does really well. If it stops working well, I will check out Waterfox. Google Chrome works really slow with my local televison news station that I check every day, and Internet Explorer, after a couple of months, wouldn't do much of anything, I have uninstalled it actually.
I personally don't think the crashes are caused by gameshs. Castleville uses a huge amount of memory, and some computers are just not up to it.
At least once a week, I do a disk cleanup, defrag, manual virus scan, empty cache's, just normal maintenance that I always did even before Castleville. It's amazing what just a 5 minute disk cleanup will do.