Encoding Multimedia

Encoding multimedia will kill your CPU... usually.
There is one quick trick that convert-my-files-while-you-get-spammed-with-malware-ads websites don't want you to know: transparent formats (i.e. those that are quick to parse).
For example, if you want to convert mp3 to opus, that's going to be quite slow. However, mp3 into flac into opus is faster! (Experimentally, approximately 200 times faster on 201X hardware.)

One disadvantage is that you may lose data to re-encoding overhead. Though in some cases, that's a benefit! Removing exif by converting jpeg to ppm to png is the easiest way to do it in my opinion.
(Just learn to use FFMPEG already, it's too good to pass up.)
(Or ask me, FFMPEG Wizard, at btdmaster ADDRESS disroot DOT org.)