I actually have a bit to say on this, coming from a lagging East Coaster with a crumb-filled toaster of a computer.
I've been playing since Ziggs/Sejuani after watching the S1 Worlds. While I truly don't believe LoL is a great game (it's good, not great. This community is so many negative points it's laughably sad), I've still embraced it because for better or worse, it's not only absurdly widespread across the world, but a benchmark for e-sports now and in years to come.
Be that as it may, my computer barely plays the game (56kb video RAM EXTRAVAGANZA). Over the years, even though my skill, map awareness, and playmaking puts me at the top in my group of friends, I've almost exclusively played Support for my entire time here because there are so many visual things that could crash me out of the game that it's easier to list off things and events that DON'T bugsplat me. However during the OFAs I found I wrecked face and carried on a team or game of Katarina's, even when grouped with people who mained her (or for that matter, owned her). Kat is the only thing in this game that gives me ZERO lag.
Kat really needs quickcasting to play her right though, so I started with her E - Shunpo. It's the kind of power you need to go off directly when you want it to, not a half second later cause you had to tap a button then click your mouse. I started playing her in TB. I beat Yasuos (he crashes me because he buys Shiv and that crashes me). I started quickcasting Q, and now even my 1 key is set to it. I played an ARAM the other night as Nidalee and chucking her spears were the easiest it's ever been.
Because I aimed for years, I know how far they can travel.
Because I quickcast I barely have to think about setting them up.
But the biggest thing about switching is I DON'T CRASH ANYMORE. I still lag, cause, hey, you know, East Coast, and Rito doesn't particularly care about us enough to actually level the playing field. But I haven't crashed. I've can buy Shivs now. My friends can play LB and Velkozby and actually get back-up from me in a fight without me getting in range and getting booted to the desktop while I curse in skype.
The thing I'm trying to say is that, if you use a sub par rig to play, and your game is unbearably laggy during big fights, try swapping to the quickcast. I have a ~85% win rate as Rammus jungle in TB, and around 60% for Kat. I actually get to be the captain for my friends, and not the blind shotcaller asking what's happening while I load back in.