I'm not sure why this happens but sometimes a single part will really react slow when I rotate it using my mouse and other time the same part will go fast. I never change any of my settings for this to change. All I do is open the part in a new window from the top level assembly. This does not happen only with this one part, other part does this also. The assembly that I opened the part from has over 100 parts and the performance is OK but when I open parts from the assembly in another window this happens.
My graphic card is compatable, I have 8GB memory on a Dell Precision M6300 laptop so I don't see why a single part should do this. My settings are shown below.