Why is my game lagging so hard

It shows I am getting 100 FPS but the game is extremely laggy and 90% of the time it crashes before I can even get in-game.

I have an intel core i5, 16 gb of ram and a gtx 1060 the game should be no problem.

 

What generation and model of Intel i5?

 

https://ca.pcpartpicker.com/product...600k-38ghz-quad-core-processor-bx80677i57600k

 

Well, this game does not like to run at unlimited fps, using vsync gives best result as long as you never drop below 60fps.

That will also help to reduce strain on CPU, GPU, PSU and motherboard.

Running game without vsync is like running stress test on your computer.

If you have gaming monitor that has higher than 60Hz refresh rate, make sure you set it to 60Hz mode when running this game as running game at 100fps without never dropping under is not feasible with current hardware.

If you play game in full screen mode, you can set adaptive vsync in nvidia control panel that is best if game sometimes drops under 60fps (if you use adaptive vsync in nvidia control panel, set ingame vsync off, it works only in full screen though), but generally you should avoid running at any other fps than 60 while having 60Hz set to monitor.

 

You should be fine then, I had to run a 3rd gen i5 when my i7 3770K died. Despite the good frame rates my frames times were very inconsistent.
As suggested above, run a sync or framecap as long as you can maintain high enough frame rates (shouldn't be a problem).