There could be a few things:
(1) Hardware issues with your computer. Check your computer's technical specs for video playback
(2) Video Codec. You may try to convertiung your videos into different codec formats and see if the speed goes up or down
(3) Update your MATLAB version and graphics driver of your computer can also help. Latest version are always fater for most cases
(4) Video files sizes might be one of the main cause of the problem. You may try using a portion of your video files
(5) How many frames chosen for playback. You may try to reduce the number of frames
(6) Check your MATLAB preferences for video playback op[tions
(7) You may need to increase RAM of your PC
All the best.
