FPS problem

Get a better computer.

Okay, this reply is gonna turn really complicated but bear (Or was it bare? I don't know which bare to use xD) with me.
First, I have the same problems as you, my FPS being somewhere around 30-70, which is still pretty terrible, considering the standards. Sooo I looked up some ways of getting your FPS up.
Here are some:
GameBooster 2: It defrags and shuts down unnecessary backround applications. It works.
http://www.iobit.com/gamebooster2beta.html
CCleaner: It deletes unwanted stuff I guess you could say, and cleans your registry of errors.
http://www.piriform.com/ccleaner/download
Get a defragging program that's good like something like I dunno, uh PerfectDisk 11 or Puran Defrag. Search those up on Google.
Well basically those should work, you could search up some other stuff, and also turn your computer to Best Performance and not Best Appearance and that should help you too, although I don't know how to get to those settings, sorry.
Welp, that's all I'm gonna say in this really complicated reply. Enjoy.