TBH an I/O system where having a file system inside a loopback device on another file system is faster than using said file system directly in the first place sounds kinda broken-ish/poorly scaling to me.
The Finder in general ends up basically being useless for me for similar reasons; I have dozens of random dependency files I don't even recognize pop up in "All My Files".
Anecdotally it certainly seems like indexing is slower on my dev drive than anywhere else, so I'm curious.
The biggest offender for me when I touch a lot of files is Dropbox. It seems to use a lot of CPU when, e.g., an Xcode update is being installed. I've read that they had to listen to events for the whole volume because the more specific APIs weren't giving them the data they needed, but you'd think they could fast-path the files that were outside their sandbox.
Is your dev drive a platter drive or SSD? I've found that the last few major releases of osx have big performance issues on systems with old-school hard drives. (Frequent beach-balling, etc.)