

One thing I ran into, though it was a while ago, was that disk caching being on would trash performance for writes on removable media for me.
The issue ended up being that the kernel would keep flushing the cache to disk, and while it was doing that none of your transfers are happening. So, it’d end up doubling or more the copy time because the write cache wasn’t actually helping removable drives.
It might be worth remounting without any caching, if it’s on, and seeing if that fixes the mess.
But, as I said, this has been a few years, so that may no longer be actively the case.



While that’s true, “I’m sorry that you got upset at what I did” is in no way actually an apology or an admission that they might have been wrong, so…