sourceFile.move significantly slows down the speed

Previously, all of my code was in a single directory. I decided to organize them and created multiple sub directories and used `sourceFile.move` (tried `moveImmediately`, `moveImmediatelySync`, `moveToDirectory` as well).

However, this operation seems really expensive. Without moving source files, `ts-morph` was taking 5 seconds to complete everything (which involves various property modifications, interface modifications etc).
With moving, it took 10+ minutes to finish. It seems it starts really fast in the beginning, but as time goes on it becomes slower and slower.

Is there any trick that I can use to speed up the process?

Update: It seems it's relatively faster when using `tsx` (3 minutes). Bun and Deno took 10+ minutes.

Start by reproducing the slowdown with the mentioned sourceFile.move, moveImmediately, moveImmediatelySync, and moveToDirectory operations, comparing runs with and without file moves under tsx, Bun, and Deno. Done means identifying the cause and documenting or implementing a validated way to avoid the progressive slowdown.

Written by the indexing model from the issue text.