For the last release, I did some basic performance tests to get the backup speed to be at par with something like rclone. I did not test sshfs specifically but I am curious how long it takes to copy this amount of data using normal tool in your setup?
My guess is that the problem is inherent to sshfs, and is not something specific to Cloudron (sshfs not being fast is pretty widely known/recognized). The only real reason I am reporting this is to perhaps suggest noting that it does not scale well in the docs, or something like that, because I don't think this gives a particularly good impression as-is.
sshfs is very sensitive to latency, so any cases where you run it to a remote server on a different network, the slowdown will be very noticable.
Using a tool more suited to this style of operation (like, say, rsync) will give better results, but it will still not scale well for large files (or large datasets, over say a few hundred GB of small files).
In the other thread, I saw that you were using encrypted backups. Is this the case when you tested this? Encryption requires a decent CPU as well, so a simple cp is not a fair comparison. I wonder if you can enable encryption on the remote disk somehow and not rely on Cloudron encryption?
Correct, encryption was enabled, but it wasn't really a factor. CPU was more or less idle while this was going on. Remote disk encryption isn't really an option in this case because I don't have physical control over the remote host, so I want to keep the data hidden