For the record, with the recent small stack fix, I see:

<verbatim>
% time clone test-clone
                Bytes      Cards  Artifacts     Deltas
Send:              49          1          0          0
Received:     1236613      26882          0          0
Send:           10025        225          0          0
Received:      104025        206         34        166
Send:           18849        405          0          0
Received:      430475        402         47        353
Send:           37649        801          0          0
Received:      391721        802         53        747
Send:           75249       1601          0          0
Received:     1401506       1602        133       1467
Send:          150449       3201          0          0
Received:     8329951       3202        527       1132
Send:          155995       3319          0          0
Received:     5152386       3320         19          0
Send:            9449        201          0          0
Received:    11672693        202         51          4
Send:            9449        201          0          0
Received:     5011269        202         19          0
Send:            9449        201          0          0
Received:     4747929        202         91        109
Send:           18849        401          0          0
Received:     2544348        402        246        154
Send:           37649        801          0          0
Received:     3850220        802        323        477
Send:           75249       1601          0          0
Received:     2532722       1602        317       1283
Send:          150449       3201          0          0
Received:     2519081       3202        216       2984
Send:          300849       6401          0          0
Received:    11316003       6402        577       2470
Send:          286467       6095          0          0
Received:     5879597       6096          2          3
Send:            9449        201          0          0
Received:     2362448        202         98        102
Send:           18849        401          0          0
Received:     1664619        402        156        244
Send:           37649        801          0          0
Received:     3444746        802        368        432
Send:           75249       1601          0          0
Received:     5068184       1602        144         21
Send:           15559        331          0          0
Received:     2669945        332        106        224
Send:           31069        661          0          0
Received:      236198        662          0        660
Send:           62089       1321          0          0
Received:      506061       1322          0       1320
Send:          124129       2641          0          0
Received:      988722       2642          0       2640
Send:          248209       5281          0          0
Received:     2033552       5282          0       5280
Send:           50903       1083          0          0
Received:     1696392       1084          4       1078
Total network traffic: 1066680 bytes sent, 28570580 bytes received
Rebuilding repository meta-data...
26881 (100%)...
project-id:
server-id:
admin-user: joerg (password is "***")
11633 (99%)...
clone test-clone  388.29s user 17.44s system 79% cpu 8:31.89 total
</verbatim>

E.g. better, but still a lot of time. Another observation is the space usage of the new clone:

Database Stats:	197170 pages, 1024 bytes/page, 149894 free pages, UTF-8, delete mode

The clone is four times the necessary size.