I fully agree here. I think that this low speed comes from the original implementation with the flag encoder method where it was not possible to increase the 4 bit spent for the storage of speed into 5 bit easily. And I wanted to have some have some room for higher speed values because of descent sections. Correct me if I’m wrong, but I think this limitation is not there any longer.
The linked route shows how subtle differences can create unwanted little detours. In this case debugging was a bigger challenge. (At the end I found that we use an IMO strange and different default for mtb regarding route networks.)
The priority issue looks strange indeed. It is caused by this inverse priority logic specific for MTB:
routeMap.put(INTERNATIONAL, PREFER.getValue());
routeMap.put(NATIONAL, PREFER.getValue());
routeMap.put(REGIONAL, PREFER.getValue());
routeMap.put(LOCAL, BEST.getValue());
I must confess that I forgot the reason why we changed that. It was during the review of #2904 in this commit.
→ Did you already fix this? Or will this be included in another priority related change?