Haiku (OS) caches the vector icons rendered from HVIF[1][2] files which are used extensively for UI.
I didn't find details of the caching design. Possibly it was mentioned to me by waddlesplash on IRC[3].
[1] 500 Byte Images: The Haiku Vector Icon Format (2016) http://blog.leahhanson.us/post/recursecenter2016/haiku_icons...
[2] Why Haiku Vector Icons are So Small | Haiku Project (2006) https://www.haiku-os.org/articles/2006-11-13_why_haiku_vecto...
[3] irc://irc.oftc.net/haiku