Question terrible stuttering and input lag whilst playing league of legends

[joelspaho1212]

has been happening for quite a while now, everytime i play my mouse and keyboard just mess me up entierly making it an unplayable experience
at the game start everything is normal.No input lag, no stuttering frames above 60-70 alls fine but during mid game or whenever i do some kind of engagement towards the enemy the mouse decides to freeze in its position and start lagging while moving really slowly preventing me from doing anything else(the screen doesnt freeze meaning that i can still see whats going on).i try to at least press some keys so i dont look like a total idiot but its no use.Has anyone else around here encountered this issue if so, do you know any solution to this problem?

thanks in advance

 

[joelspaho1212]

my specs are really low end however i doubt its the reason behind the stuttering as the game was running just fine a month ago.i dont know if its worth mentioning however my system was running slowly so i decided to reinstall windows before doing so i ran across uefi i didnt really know what it was so i just looked it up to find out that not only its faster and better but my motherboard supports it too, so i decided to change the system from bios to uefi and install windows in it, after formatting my disk and converting it to gpt all was good.This is the only thing that was done to the system prior to the annoying lags, literally nothing else.
specs:
core 2 duo p8600 2.4ghz 2cores/2threads
amd mobility radeon 3650hd 512mb gddr3
3gb ram ddr2
like i said its totally unlikely to be the specs causing the issue as the game was running just fine before the formatting and uefi conversion the lagging has been happening eversince i converted.if uefi is the reason why im lagging could someone explain why that is?