First of all, I want to say I appriciate the fact Riot has jumped on this issue. I love this game and really don't wish to seem like I'm demanding everything for nothing. (It's a free game, I have no sense of entitlement in it)
Before the patch, I never experienced lag issues. My FPS was always consistantly at 30 no matter what was happening on screen or how many programs I had running. I would run LoL through Steam while on a Skype call in the middle of a full team fight and never experience any frame rate issues.
Post patch however, I cannot even attack the wraiths in our jungle without dropping below 15 fps. This is with no other programs running, all graphics set to very low, a fresh reinstall, processor throttling turned off, updated video card drivers and process priority set accordingly. In other words I have attempted every possible "fix" and have determined it cannot be on my end.
Since spectator mode has been removed, I still experience issues. I just recently tested 3 custom games by b-lining straight to the jungle. I still experienced FPS drops when there were no other champions on the map. I will continue to try the game and see if it gets better.
Also, my fps seems to fluctuate more now. Pre-patch it was always around 30, never went highier than 32 or lower than 28. Now at the start is may be around 45 or 50, then drop to 20, then raise to 30, then 40, then stay at 40, then drop to 15 or below during fights. It's very inconsistant compared to previous games.