I'm not saying it isn't irritating, or that having a shiny SSD wouldn't be be awesome, or that Firefox is turning into bloated software - because those are all true statements. But when put in the context of:
A) wait 2 seconds
B) Buy a $200 hard drive
C) Fork Firefox yourself
waiting the 2 seconds seems like the sanest solution. Perhaps I've been working on budget hardware for so long that it doesn't bother me anymore, but the delay just doesn't seem like that big of a deal.
I imagine checking your email or reading HN kills more time per day than waiting for programs to start.
Few second wait times are a real burden to me, because it's too long to go do anything else productive, but still slow me down.
And when this happens multiple times per day for multiple apps - how much coffee can you drink?