“enhancement would also improve browser stability”
there’s no programmatic reason it should.
Ya. Normally the opposite is true. And color me unimaginative but, if you have a multi-core processor, it’s already fast enough to run any browser with ease, one a single core.
They may be planning on isolating plugins etc. in threads other than the main browser thread. Something bad happens, it is only that thread that throws an exception. As long as the OS doesn't kick the entire process... It could be more stable. Thread gets into a runaway recursion and jumps it's stack? Handled... etc.
I've done a fair amount of multi-threading work, and by and large it does make programs more stable. You can do all kinds of nice clean implementations: park a thread on something waiting on IO, etc. You don't have to play polling games hoping your buffers don't overflow etc. You can be even more object-oriented, class X does Y, period. You don't have to call into it periodically to give it CPU time, etc.