You have a lot running in the background, that can cause a lot/some/no issues for many reasons. A quick way to find if any are lurking with background apps is to run MSconfig via "run" on the start button.
Stay offline when you do this as it will probably stop your firewall & anti-v loading after a boot.
When its up, look at Services tab, check the "Hide MS Services " box, press "disable all", go to the Startup tab, press "disable all" button.
Go back to Services Tab and make sure the "hide all MS Services" tab is checked (ie not empty)
Then press ok. ReBoot.
When it settles, run the game - if the symptoms have disappeared - either the background apps in total are stealing too much main system RAM, or one (or more than one) is clashing in memory. In the latter case, its then a detective job to find out which one by turning them back on one by one.
If you get "in a pickle" just go back into MSconfig and enable the top button on the front screen -= that will return you back to normal.
Regards
Zy