One reason we want to disable or remove 60fps is because of video buffering. Our internet speed is just not fast enough to stream a high framerate video, and/or we just prefer to watch lower 30fps video.
There are several ways to disable or turn off 60fps on a Youtube video. This can be done by using a chrome extension.
One extension that I have found to be very simple at setting this up is called h264ify. This extension is made to help smoothen Youtube experience on chrome for low-end computers which probably using too much CPU power for these computers.
Simply checking the box "Block 60ps video" and 720p videos and above will now
play at lower framerate.
Read also : Watch Multiple Youtube Videos at Once