Looks like you're using a laptop. Could be a thermal issue. There is a program called Real Temp you can use to monitor your CPU temperatures. That is a good place to start. MSI Afterburner can monitor your GPU temperatures. If you notice your CPU temps getting over 80 degrees Celcius you should check for CPU throttling by the operating system. There is a program called CPU-ID (CPU-Z) you can use to monitor your CPU frequency. If the temperature is getting high and the CPU is being throttled as a result, then you need to figure out how to keep your laptop cool enough to stay below the temperature sensor's throttling point. To that end, look online for reviews of laptop cooling pads and such.