@guy038 said: Now, I did a test, searching in all files of my D: USB key, with : The native N++ Find in Files dialog The Search++ Search in Files dialog The MultiReplace Find All in Files command To be sure to process fair tests, I unplung my USB key, re-start my laptop completely, replug my USB key and starts a new N++ session, before running these three Find in Files operations, in turn ! I searched for the Fi string, with the Match case and the Regular expression options checked. I got : 27,112 matches in 833 files of 1,761 searched for the N++ Search Results panel, in 1m 37s 27,112 matches in 833 files of 1,761 files for the Search++ Search++ Results, in 2m 21s 27,087 hits in 835 file(s) for the MultiReplace Search results panel, in 1m 36s I have been struggling with how to optimize the multithreading of my search for over a month now. Among other things, I’ve found that most everything I thought I was measuring wasn’t what I was actually measuring. One surprise I only recently discovered was that even if I eject and unplug a thumb drive and then plug it in again. there is still a “first time today” cost in the time it takes to read it. Windows is persisting something and it is able to identify the same drive, even though it’s been unplugged. I don’t know the exact time, but Windows on my machine keeps it for more than an hour and less than 24 hours. Running a particular test the first time I plugged in a particular USB drive I have, it took 8 minutes and 26 seconds. After ejecting the drive, unplugging it, waiting a moment, plugging it back in and running the exact same test, it took 20 seconds. This drive appears to take whatever it is that Windows does once a day (?) exceptionally hard. Most drives don’t show anything so obvious. This is the only drive I have tested so far that uses FAT, so that could have something to do with it. I haven’t yet tested whether rebooting is enough to reset the “once a day” penalty, or if it persists in something that isn’t lost in a reboot. It may have something to do with antivirus, though I haven’t yet proven any such thing. So I’m wondering, if you happen to remember, whether you tested in the order you listed, or whether you happened to test Search++ first? In any case, after weeks of running in circles, I think I will soon give up the fight to optimize performance and see what else needs work.