I have a similar problem. It was compiling fine a few months ago on my Windows 7 PC - I haven't used the Arduino IDE for a while - and now it is taking ages to compile.  Getting stuck halfway, will eventually compile if I leave it long enough but taking a few minutes to complile a simple sketch such as blink.

I have installed latest Java, switched off bluetooth, switched off AV - all suggestions I have seen suggested on the internet - but none solves the issue.   

The PC resources are fine - plenty of CPU/RAM, can't see any run away tasks running.
Other aspects of IDE work fine, even the upload stage - its just the compile that is slow.

Any suggestions?