@AureateFlux: Ah! I'd actually noticed the Wicket thing, something like five years ago, but shortly forgot and never thought about it again. Thanks for your responses to my questions, but haHA, look again. This story, as well as my original post, are from A YEAR and two months ago! That may explain how you missed it, eh? :D
@StormtrooprDave: @Hongo: It does that to keep Flash stable... As crazy as that sounds. Basically, in an attempt to keep things running smoothly, they made it so that if a flash object was unresponsive for a few seconds (it happens), the plugin will crash. I have no idea why.
I disabled that feature, but it still handled flash so poorly that I downgraded to the last version I remember really enjoying the improvements of.
Even after upgrading to 3.6.6, the new "plugin container" program was giving me trouble, so I went into about:config and completely disabled the timeout function. It was still causing severe problems, though... Which is why I'm writing this from the comfort of 3.5.10, with update checking switched off (for the time being, at least).