Empire: Total War
As far as I can remember this has always been a pain in my butt too but it is something you have to live with. Thirty seconds to one minute isn't that bad, besides it lets you see how the battle fields are unfolding and coming to be.
Bottom line, it is probably both but dont bother spending money on some more memory and a new processor.
• Unlimited Movement
• One Turn Construction
+ 12 more options