I have already seen this thread about 1fichier, but I though maybe something has changed in the meantime, so I invested 3 EUR to give it a try.
So in case anyone is wondering, it still works exactly as described in the previous thread, i.e. there are very hard limits and due to forced delays the upload of a lot of small files is incredibly slow. I am getting speeds only about 1 or 2 % of what other hosters are able to achieve on my 30 MBit/s upload connection (Backblaze B2, Jottacloud).
However when testing large files, the situation is different and the upload happily runs at 100 %.
So for me with hundreds of thousands files I won't bother and will go through the Jottacloud route.
Actually see that it isn't just slow, but the upload stopping, and waiting. For example there are 4 smaller files, about 4 mbytes in total, as each minute the progress reports appear i can see that it no any progress happens, then boom xy: copied (new) for each, then next 4 files, standing there for minutes, then suddenly all uploaded.
Same time for large files, the upload is at 20-25 mb/sec.
So uploading 10x0,5-2 mbyte files take much longer time than to upload as many but 1-5 gbyte files.
And the reason is: DEBUG : Sleeping for 30 seconds due to: HTTP error 403 (403 Forbidden) returned body: "{\"message\":\"Flood detected: IP Locked #374\",\"status\":\"KO\"}"