Sounds to me more like a memory problem. Open the task manager when this starts happening, then click the performance tab and see if your page file or something else is getting too big 
   
 are all your drivers up-to-date? 
   
 Could also be a bad video card though I would look at that as a last ditch item. I've had that happen to me in the past.  My issue was zoning,  every time I zoned it took longer, and longer until it got in excess of 5-6 minutes to zone.  Replaced the card and all was well 
		
		
		
		
		
		
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