Adding new version somehow broke earlier version + slow

I had 2.78 and decided to install 2.79. I just installed a new hard drive and wanted to see if I get any performance boost from it. My problem is that blender 2.79 seems to work ok but slower. All my addons were supported. But 2.78 somehow broke. It is not a major issue but when I close 2.78 it kills the program but blender.exe is still in task manager using tons of cpu and memory. It stays on until I kill it manually. As far as I know I did not do anything to my 2.78 install. Just copied my addons from it.

Also another question I have. Blender never seems to use more than 25% of my cpu (excluding anything rendering related)? Sometimes when I have lots of particles-converted-to-meshes objects blender slows down to crawl when I select stuff, add modifiers or unlink the objects… but I can’t figure out what is slowing it down. Cpu peaks at 27%, gpu use is 360mb memory and not even 1 percent gpu. Hard drives are not doing anything or very little and memory is used about 60% of all 8gb. It is an intensive scene, about 15000 objects… but what exactly is my bottleneck here?

Windows 8.1, i5 4460, gtx970, 8gb ram

The mature 2.78 running on a hard drive is different in terms of optimization. With a new hard drive, the system is basically an infant machine. It still needs to determine which function, algorithms and etc…to optimize based on usage. It may never reach the level as maturity of the old system to your liking. What I do is I do some basic tutorials show the stupid machine know what I do…