|Where are you checking your temps? Which ones?|
Use HWMonitor to check them all. Leave it running minimized while playing and you can see min, max, and current readings after. You might have a decent system temp and CPU temp but your GPU or other temp might be peaking and being throttled back for a few moments to dissipate the heat. HD Graphics 4000 means that you are using the onboard graphics, this means that the CPU and GPU are on the same die and have to share the same heat sink so there is a possible issue there. Then there is the HD graphics which are not really gaming graphics so if this is a desktop, seriously consider a gaming graphics card (GTX750, equiv, or higher).
As also mentioned, check in Task Manager to see what is hogging system resources, it might even be your antivirus program. If there are programs installed at the factory that always run, they might be the problem. If you do not use them you can uninstall them. If you use them, you can check in their settings to make them so that they do not start with Windows and close completely when you shut them down.
You have to be a little bit crazy to keep you from going insane.