1. The version of Windows you are running has a limitation which causes performance issues in hardware accelerated applications (such as games) if multiple monitors with different refresh rates are present. Your system's monitors have 2 different refresh rates, so you are affected by this limitation.
To fix this issue, we recommend updating to the Windows 10 May 2020 Update. Follow
these instructions if you're not sure how to update.
2. If you plan on streaming or uploading those recording please be aware that having the YUV Color range set to "Full" will cause playback issues in certain browsers and on various video platforms. Shadows, highlights and color will look off. In OBS, go to "Settings -> Advanced" and set "YUV Color Range" back to "Partial".