With [d16ccde510] and a fresh trace of pkgsrc, fossil clone now takes:

<verbatim>
real	5m41.922s
user	1m52.690s
sys	0m15.750s
</verbatim>

...until the rebuild starts. IO delays can be neglected and this is completely dominated by insufficient asynchronous processing between client and server. This time is not masked by network speed either.