Use the Performance Monitor found in Task Manager to assess your PC under different working conditions. If you can put a second screen on for the task then that is very helpful. Otherwise you may have to record the Performance Monitors findings if the application you are testing with demands to run in the foreground. If your CPU is constantly at 100 % or your RAM is hardfaulting a lot or your Disk Queue is constantly high then you are looking at bottlenecks. Use GPUZ to assess the loads placed on your GPU.