Rarecomponent123, 
You may find that some / many of the problems you are having could possibly go away if you do happen to upgrade to a higher version of SONAR …
I skipped Windows 7 all together and went from XP to Windows 8 64,  then I upgraded to SONAR X3 Producer …
To say there was a learning curve to crest would be an understatement …lol 
One thing that may interest you is I wound up picking up Music Creator 6 for XP ….
it was a nice little playground to learn some of the X ways of doing things on a familiar at the time to me OS ..
At the time I was still bouncing back and forth between X3 on Win 8 and XP ….
One thing that I found out very early on was even on XP the audio engine of Music Creator 6 ran circles around my SONAR 6 PE audio engine ….
I had S..6 projects that had lot's of plugs and plenty of audio tracks ,  when I opened these projects in MC 6 I had a lot of extra headroom to spare ….some of these projects literally brought SONAR  6 to a screeching halt …
That experience did open my up to the fact that things have indeed come a long way performance wise w the SONAR X version of the Audio engine …Yeah , if I hadn't tried it out for myself I wouldn't of believed it 
I think it is very possible that you may get much better performance using a newer version of SONAR  on your current machine .
If you need to , you can always use 7 until you get comfortable learning the in's and out's of the upgrade …
 
all the best , 
 
Kenny