Okay, let’s step back a bit…
If a system is running unusually slow, it’s generally caused by:
1. The system is busy doing other stuff that takes too much time away from what you want it to do, or
2. The system memory resources are being used to the point where the OS has to swap memory out to a slow hard disk, or
3. An application is going wonky and takes all the processors’ effort, or
4. Other stuff I can’t think of off the top.
So to figure out what’s going wrong with your system, you should try to simplify and isolate. Check to see if the system is busy doing other stuff (maybe it’s downloading updates in the background, or has too many applications running that require processor time, etc.), or check to see if it’s running out of memory (leak, etc.), or one of the applications is hogging the processors. And to check to see if it’s solely a Carrara issue, shut down all other apps and just focus on Carrara.
Whether you’re also running Chrome and Photoshop really doesn’t matter. What matters is if they are causing the problem or not. If there’s a lot of disk activity when the system is “laggy”, then that’s good information. If the memory used by Carrara goes from 1.2GB when you load a scene, to 12.3 GB after 6 hours, there’s a problem.
Again, simplify and isolate. And again, Task Manager is your friend. It can tell you how much CPU time each app is taking, how much memory, as well as graphs of history, and whether the system is busy downloading stuff in the background. And check the disk access light(s), they’ll tell you if the disk is working overtime and slowing things down.