Frequent Minifreezes

Recently I've been noticing that my computer seems to have frequent short (maybe around half a second) freezes no matter what I'm doing. I notice it most when playing videogames, where the screen will freeze for a while before returning to normal. It's also noticeable when typing in some programs, where i will see nothing come out until a few seconds after I've typed it. When watching videos on the internet, the video will randomly freeze at a frame for a while (with audio still going) before skipping to synch up with the audio. If the videos are on my hard drive however, the problems are much more noticeable; Both audio and visuals stutter almost constantly. I first noticed this problem around a week ago when the sounds of a game i was playing (League of Legends) kept repeating for several seconds each time they played.