strange laggines when using skills, accopmanied by beeping

So, I've been playing irelia and in middle of game whenever i tried to cast a spell my game would freak out. for few seconds my mouse responded for a single frame every 0.5 sec and so would my keyboard. The game was running smoothly though. I restarted it and for a the timei was in base, everything was fine, i could use w and e without the lagginess, but the moment i got out of base and close to minions, it started again, this time with screen lag. i tried to write in chat and it would write 1 letter every 0.5 sec even though i wrote the whole sentence in 2 to 3 seconds. I could move normally as long as i didnt use skills. the beeping was heard only if i was moving mouse if i used just skills, the game would lag but there was no beeping until i moved my mouse. It dissapeard by itself in about 5 minutes.