Agreed, assuming normal amounts of RAM/caching. That detail was not in the original post so the possibility of lots of small files was still there.
Did you test speeds with your setup before buying and find they were OK then, but then ran into issues when trying other thing after buying?
I am wondering if speeds are fast in some tests/situations and slow in others, which may point to a cause and possible solutions.
I understand that, but without seeing the data or being able to reproduce the setup, I have nothing to go on. I can tell you that when I copy large files, speed is identical to everything else. Which of is is "right?" Probably both of us, and the differences come down to the details of what is being done, which are important.
Sometimes differences also come down to how the data is being interpreted and differences in how different programs represent progress, and so on. Possibly not in this case, but I can't rule it out without knowing the details.
Have you checked copy speeds with other types of device? How do things perform when copying between two local SATA drives? If performance is good there then it means we should focus on the type of device involved, and that we may need to get hold of similar hardware to test against ourselves. On the other hand, if the same performance issue exists with a vanilla local SATA->SATA copy, then we can rule out anything to do with the type of device and look in other directions.
The vast, vast majority of people find copy speed is identical between programs when doing proper tests (avoiding caching, and per-file overheads that are different in each program, and so on). This should generally be the case because Opus is literally just sitting in a loop waiting for the OS to copy the data, and not doing the low-level work of reading/writing each bit itself.
There will always be edge cases where one program is faster than another for particular scenarios, but we aren't aware of any major ones. You may have found one, in which case we'd like to know more about it to help us reproduce what you're seeing and look into where the difference is coming from.
Many other file managers just ask the Windows shell to copy files for them, in which case (unless antivirus is doing different things to different programs) performance is identical to Explorer as it's literally the same code being used. (Which also has the same limitations, as the downside. You can call the shell file copy APIs in Opus if you wish, but it blocks off a lot of functionality. Still, it can be useful when doing basic file copies to devices that are only fast when using the shell APIs.)
As an example: Companies who make NAS devices do a lot of testing and optimising with Explorer, since it's what most people will use and judge them by, but sometimes leave giant performance issues (or worse) in their devices when other programs do things even slightly differently. I'm not saying that is the case in this situation, as I do not know and cannot test it, but it has been found to be the case in others.
e.g. People checked how fast a drive performed when Photoshop loaded and saved data vs when Explorer copied files, and they saw the drive was very slow for everything except Explorer (and other things using Explorer's file-copy API). Sometimes those issues are resolved by updating the device's firmware, but curiously they sometimes come back in new devices, indicating that some brands do not carry forward all of their fixes from one device to another.
If you don't want to try things then there is not much we can do. I can suggest settings that may help (e.g. try turning on the non-buffered I/O option in Pefs/Misc/Advanced, setting it to 1MB), but copy speed issues can be caused by a large array of issues, and we have no way of knowing which one without working through the different possibilities and trying various things.
