* If using VLC media player, go to Tools--> Preferences --> Video --> Output.
By default, the Output is set to "Automatic".
Go through the list and try out other output options to see if any makes videos run smoother.
* If using mpv media player, you may be able to improve performance by entering `mpv --profile=sw-fast --vo=x11` in a terminal.
* For video lags when playing videos from a browser, disable hardware acceleration in the browser. If the problem arises when watching streams, it may be smoother to use `streamlink` to view streams in mpv instead of using the browser.