when looking at macOS, cached files memory doesn’t matter, at all. as long as there are no swap used stats, it’s actually good macOS is caching file data. As long s it releases cached files if any apps actually NEED that memory. But macOS is designed to use memory for caching vs just letting it sit free/unused what so ever. Don’t focus on how big caached memory is. it’s an insignificant stat
App memory should be looked at if it seems the heap size of a specific app is much higher than normal. 9.0 would be higher than 8.3 but probably not too much higher (when considering similar settings/hardware)
TL/DR, just make sure you aren’t running out of memory and seeing compressed memory or virtual memory pageouts.
For perspective, I have 64 gigs of ram. Apps are using 24, and 24 gigs are being used for cached memory. only 16gigs of free memory. Compressed memory is at 0 and pageouts are at 0. I have two copies of wow running, each using 4 gigs which is pretty normal.