Tip to those with client start up issues/client stability
Open your main HDD/installation driver location on your computer Riot games folder then just run the admin version of the start up.(client) It seems to run smoother and I see increases in FPS and overally stability. There is minor black screening which happens while at the loading screen though, this will fix itself and will correct around the area when everyone is at 90%-100% loaded in and you'll be loaded in as well obviously and will generally only occur if you're an ALT+tabber like I am constantly popping between multiple games while waiting for league to get to that loading area when you can actually pay attention to it :D...
Anyway, figured I'd let those that don't know know about it. I've been doing this awhile the new client/patcher has always given me issues but running it manually through admin has definately improved the stability of it.