It seems the easier (older) the video codec format the bigger is the file but also the less CPU&#x2F;GPU resources are required to play them.<p>Remember Windows 95 played AVI videos e.g. in the file copying dialog. The AVI video consisted as a series of BMP pictures. All magenta colored areas where interpreted as transparent. (info about the special bitmap based AVI format:   <a href="http:&#x2F;&#x2F;www.endurasoft.com&#x2F;techtalk&#x2F;AVI.aspx" rel="nofollow">http:&#x2F;&#x2F;www.endurasoft.com&#x2F;techtalk&#x2F;AVI.aspx</a> ) A 486 66 MHz with 4MB memory could play that short small videos. The Win95 CD contained two movie trailers afaik with an early Intel video codec, it took a more powerful Pentium 1 CPU to play them at 320x200 (Intel Indeo codec: <a href="https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Indeo" rel="nofollow">https:&#x2F;&#x2F;en.wikipedia.org&#x2F;wiki&#x2F;Indeo</a> ).<p>Coming back to GIFs and MP4&#x2F;HTML5 videos. GIF is an old format from ca 1989, showing them is less CPU intensive than playing MP4 videos. Firefox on PC and all mobile browsers on iPad and Android that I tried had serious performance issues with 100+ very small videos. Interesting that GIFs mobile devices with even just 512MB memory can show at least 100 GIF videos (each 5-15 MB filesize) on one page.