I don't think there is any bottleneck.
why don't you run the performance benchmark and see how it does?
I know I'm going to sound like a broken record but did you make sure you're using a certified video card driver as listed on the Solidworks website?
A couple of questions:
What Solidworks version are you using?
Do you have "Use Software OpenGL" checked in your options (you probably don't....but it pays to check)?
If you DO, then that is certainly your bottleneck.
However, if you don't.....then I would guess that the issue is your Graphics card. It is not a bad graphics card at all....but I would say that you may be pushing it to the limits with larger assemblies.
See the drop off in performance between the P2000 and the P1000 (in the link above)?
I am using the P2000 and this problem has gone away for me. Although admittedly I have also upgraded to a faster CPU as well....so this may also be a factor. But I am thinking that this is squarely in the Graphics card's department.
The threads I'm suggesting you contains all the info you need to optimize your system performance for solidworks
In short you can do following things:
1. open assemblies in lightweight mode.
2. Use Large Assembly Mode.
3. Use Quick view mode (if you just wants to see the model and not to edit it)
4. Increase Virtual memory.
5. Increase GDI value ( Don't do this if you are not familiar with editing registry)
But First of all Check this site Graphics Card Drivers | Hardware & System Requirements | SOLIDWORKS
Check the background processes.
If your CPU is at 40% its likely the bottleneck. Checking the cpu graph for the core SW is running on will help you figure out if it is.
You should look at the cpu graph after setting SW's cpu affinity to the core with highest clock (if they're not all the same.)
Running the bench mark and comparing your system to similar systems will also help.
Realizing this is an old post but the "sudden locking up" sounds like what happens when Autorecover is saving
System Options -> Backup/Recover and disable Autorecover if that's the case
I've also seen behavior like that sometimes caused by Antivirus or other 3rd party utility
in my opinion, you need a solid state disk， the software will lunch faster, also open files.
Windows 7 64bit
32GB DDR3 PC3-12800
Nvidia Quadroo P1000