Why are my games suddenly running so slow?

I recently got NEW ASUS x550C laptop. I've been playing some games that I got for it and they were running great! Most of the time around 40 fps. I had all the graphics settings on low so that I would actually be able to run them though. My computer needed an update so I turned it off and let it do it's thing. But now whenever I go into games I can barely run anything! All of my games suddenly seem to be running at around 4 fps and lower. Now these aren't your simple games. An example would be World of tanks. I could play it at....yes 45 fps. But now it's suddenly at 4! Is there some way to get my games back? I know my processor isn't exactly the best but that doesn't explain why I can't even play anything now... the specs are... CPU: Intel Pentium ULV, 1.8 ghz. Memory: 8Gb ram 750 HDD OS: windows 8