Interesting story tangentially related to this question. I just finished building my new gaming rig - the only thing left is a GPU which should be coming in the

Interesting story tangentially related to this question. I just finished building my new gaming rig - the only thing left is a GPU which should be coming in the mail pretty soon. The CPU I have, a core i7 4790K, has a pretty decent GPU so I was testing it out the last couple of days. The first game I tried was GTA 5. It ran smoothly (albeit at the lowest possible settings and 720p resolution). I was pretty impressed with the integrated graphics' performance. Yesterday I tried GTAV out again for a little bit and I observed that it was ... way too choppy and basically unplayable. I couldn't figure out the reason why. Then I saw that Thunderbird was the only application that was open aside from Steam and GTAV. I closed it down again and boom, back to consistently high framerates. What is the catch here? Granted I'm using the integrated graphics that came with the CPU but I have 32 GBs of RAM. What gives!??