I probably don't have the massive libraries you do but I find that if their all named descriptively then the newish feature reaper has to "create database" from a chosen set of folders works well for me in the media explorer.
It's a bit of a cheat as what you get it a massive list of all the files in that set of folders but that means you can search from the top bit.
No where near as well done as cubase, soundminer etc but very fast for what it is and free
