Originally Posted by
Spider-Dan
It does force a server check; the icon/proc for Firestarter will pop up earlier than if you wait for the "natural" proc. It pops up around the middle of the F1 animation instead of at the end, which is maybe a 0.25~0.5 second advantage.
That said, I'm not convinced it translates into any practical gain, as you still have to wait and push F3 after the proc. If you pushed F1 instead of, say, Lethargy, then at the same moment you execute Lethargy and can see the Firestarter proc, you could already be Lethargy-execution-time into your next F1 cast, plus your reaction time to hit F3.