Client is very slow and laggy after reinstall

After several updates ago to the client, I began to have problems in my champ select and the results screen. It would take like 4 seconds too long in champ select, not giving me enough time to call what role I wanted to play. The results screen takes about 4 minutes to load after end game. i got sick of it finally and uninstalled it and reinstalled the client. Now I'm having unbelievable lag problems and the whole client is slower than ever. I have yet to play a game, because it has been updating now for 3 1/2 hours and still is not finished...I can only imagine the lag I will receive once I actually play the game. I looked in past forums for similar problems and nothing has worked. Someone please help this is so frustrating and I might just quit LoL if this isn't fixed :(