http://bugs.winehq.org/show_bug.cgi?id=35388
--- Comment #7 from Johannes Brandstätter jbrandstaetter@gmail.com --- I did some more tests and found some strange behaviour.
While trying to bisect from 1.7.10 to 1.7.11 the reported issues were gone. At first I thought that all those commits are good and continued, until I reached one of the last steps, and with the final step confirming that the problems were really gone.
I made sure to test everything again in a clean prefix, which did not change anything.
Apparently if you run LoL without the Air client the game runs just fine. I have no idea how this adds up, but it works for me.
Running LoL without the Air client is as easy as going to http://www.lolnexus.com/NA/featured-games and select "Spectate", using the command line given here it just needs some changes to make it work with wine.
I had to override d3dx9_36 (installed with winetricks) and msvcp110. Windows version was set to Windows 7 (tried XP too, but that did not change anything).
I want to add that I did not experience any FPS issues, did not try the map "Howling Abyss" though.