Hi @guy038,
thanks for testing again! In case you’re curious, here’s roughly what the new loading threads in 6.2 do.
As soon as the file list is known, a few worker threads start reading ahead: they open the files, read them, check for binary content and decode the text. The main thread takes the files in list order as soon as each one is ready, puts it into a hidden Scintilla document and searches it. So the hits and their order stay the same, but reading and searching now overlap.
On a USB stick MultiReplace uses four threads by default. With a cold cache, as in your test, most of the time goes into waiting for your USB key, and that is where it helps: up to four files are read at the same time, and the search runs while the next ones are still loading.
If you want to see what the threads bring on your key: with LoadThreads=0 in the [ReplaceInFiles] section of the INI file, every file is read on the main thread as before (see the README; it takes effect after restarting Notepad++).