Suddenly lagging in every game I try to play?

Hi everyone!

I was just playing counter strike when suddenly out of nowhere my fps dropped down to like 20. I thought "whatever, it might be a random lagspike, happens sometimes". It has always been at 100 and only sometimes drops to 90-95 but now since this "whatever lagspike" it just hasn't gone up from 20 fps and sometimes drops back down to 5 or 10 which makes my game totally unplayable. I then decided to check other games to see if its only cs but no, other games all of a sudden lag like hell also. I have no idea what to do, one moment i was playing constant 100 fps and now i can't get over 20 fps?

I checked graphic driver updates, there were no updates. I tried restarting my computer multiple times, no change. Then I tried updating java since one of the games i tried playing needed it, still nothing.

I monitored my cpu and motherboard temperatures, they were all fine?
Windows 7 is performing a little slower but not significantly. My cpu used to be at like 20% load to 50% load when i was playing games and chrome was open in the background but now it's at like 80-100% but they're the same apps running but now suddenly they take more cpu than before that lagspike occured.

Could someone please help me and explain howcome one second I'm playing sooo smoothly with 100 fps and now my computer can't even hit over 20?

Thanks!

looks like i figured it out, it's weird but it looks like i started lagging because the powerplan of my laptop was on energy saver because i had taken it with me and the battery of it wasn't that good. Now i plugged it back in and change powerplan to high performance and it works perfectly again.