Compile time is to slow

I am using C#. Recently my compile time increased way to much to be normal. Every time I change something it takes about 1 to 3 minutes to compile.
On another computer it compiles in about 10 sec. So something is wrong on my computer.
Does anybody have an idea why it takes so long on my computer?

I have an i7 2.3 GHz processor.
4GB RAM

First make a back up of your work → DO IT.

Perhaps something is messed up in your Lib folder. After backing up, delete your Library folder(without unity running for good measure), open your project back up and let it rebuild and see if that helps. Totally a stab in the dark though.