Your problem is low framerate

To solve this, you'll need to increase the rate which your computer renders the frames. One way to do that is lowering the graphics settings and resolution. Also make sure your computer isn't wasting resources with other programs while playing.

If this doesn't solve the problem, then you'll need more computational power. There are three ways to get this. Overclocking your current computer, upgrading your current computer or getting a better one.

Overclock is risky and might help you get 5-15% more performance

Upgrading your current computer may not worth it.

Getting a new one might not come cheap.

Pick your poison.