[Borgbackup] [Documentation] Remote/ local usage

[nerbrume at free.fr]

Hello,

I've just setup borg between a rather recent desktop machine (local), which is distantly backuped (ssh) on a very small box (something like a raspberry pi 1st gen, but with even less RAM).
I didn't found in the documentation any reference as to which operations are done where (and what parameters I can act upon to lessen the burden on the slow distant machine).
(btw, the doc is great !)

My main concerns are the CPU and RAM usage during backup (I guess disk usage would be of interest too, but I didn't found it to be the limiting factor) : 
- where is the compression (lz4/gzip/lzma) done ?
- where is the encryption (ssh + borg own encryption) done ?
- where is the deduplication done ?

But I'm also interested in the same question during other borg actions, especially borg check. 
I've already gathered from my observations that borg mount is done locally : mounting my backup locally on the small box takes forever.

I feel this info should be in the documentation, but refrained from submitting a bug. Tell me if I should.