I know that is too late in case it is real... I barely used aim assist, but I have recently noticed that something consumes significant part of my (I must admit extremely old...) CPU when I use Sonar.
I have started to look what can course that and has found that is aim assist. When the track view is full screen, my CPU spikes all the way up.
I remember such problem long time ago, but I also have X3e installed and I do not observe such effect there.
 
I know most people here have modern computers, but can someone confirm the observation in the latest platinum?
So, just one track with one clip, full screen, fast moving mouse with Aim Assist spikes CPU (f.e. in the Sonar Performace monitor, set to "System performance").