то есть офф вики коди гонит?
Increasing the cache
Here we can do two things:
Value: 20971520 (or any value, in bytes) - keep the cache in RAM, but increase how much RAM is used. The number is the buffer size in bytes (20971520 is the default, which is 20MB, which requires 60MB of free RAM). Kodi will not buffer ahead more than this. Note: For the memory size set here, Kodi will require 3x the amount of RAM to be free. Setting this too high might cause Kodi to crash if it can't get enough RAM.
Ну вот по моему наоборот, может в 18 версии сломали, на линуксе ставил 450, получал реальных 150. Надо в мониторе ресурсов ещё глянуть