Hardware Acceleration allows your browser to utilise your GPU to speed up rendering.
Unfortunately, when playing intense or poorly optimised games on your computer, a web browser placing a sustained workload on your video card can adversely impact your framerate. In addition, depending on your driver version your GPU's clock speeds may behave unpredictably while you are both gaming and using a web browser which has Hardware Acceleration enabled.
Thus, as a troubleshooting step it is recommended that you consider disabling Hardware Acceleration.
The steps for doing so on some common web browsers can be found below.
chrome://settings/?search=acceleration into your browser's address barUse graphics acceleration when availableedge://settings/system/manageSystem#GraphicsAcceleration&1 into your browser's address barUse graphics acceleration when availableabout:preferences into your browser's address barUse hardware acceleration when availableopera://settings/?search=acceleration into your browser's address barUse graphics acceleration when availablevivaldi:settings/webpages/ into your browser's address barUse Hardware Acceleration when Available