Start VLC, click on Tools at the top of the main window, then Preferences, then Input and Codecs. Put a check mark in the box for GPU accelerated decoding. This will only help if your video card is capable of such processing. It is something to try anyway.
Under the Video section, VLC should already be using Overlay (accelerated video output) using the video card. You can toggle this off and see if anything changes, but I really can’t see it helping.