your virtual memory is affected by programs you have running in the background. right click on my computer, choose properties and then performance. your performance should be above 90% for Unreal to have enough virtual memory to perform the tasks. You can close them easily by going to start button, and run and type msconfig and then choose the start tab. there you can customize what programs you want to open on start up. you want the least amount, like virus protect, systray..eve ICQ takes up virtual memory so you should close it while you play. these things helped me get my percentage up to 97%. Hope it helps you.
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