Wow, this question seems to come up almost every day. It would sure be nice to have a FAQ in this forum so we don't have to go over the same ground over, and over, and over again.
Here's a link to some advice I have given to many people:
If you search, you will find several dozen threads with additional advice.
Here are links to other threads where I gave this same advice. I am providing these in order to give you links to other threads where people were having the same, or similar problem:
kairosmatt - yesThe title subject of this post is: "60fps stuttering playback". I answered that question. Apparently I wasted my time posting that answer.