$ inkscape -V
Inkscape 0.48.3.1 r9886 (May 10 2012)
$ inkttt -V
Inkscape 0.48+devel r11487 custom (Jun 11 2012)
$ 

$ ll 152*
-rw-r--r--  1 su_v  staff  7348784 Jun 11 19:05 152x152-16-groups-2c.svg
-rw-r--r--  1 su_v  staff  6844858 Jun 11 18:35 152x152-clones-unlinked-2b.svg

### 152x152-clones-unlinked-2b.svg
### 22846 objects in Layer "tiles2"

$ time inkscape -f 152x152-clones-unlinked-2b.svg --verb=FileClose

real	0m16.852s
user	0m16.140s
sys	0m0.367s
$ time inkscape -f 152x152-clones-unlinked-2b.svg --verb=DialogXMLEditor --verb=FileClose

real	0m37.909s
user	0m37.334s
sys	0m0.404s
$ time inkttt -f 152x152-clones-unlinked-2b.svg --verb=FileClose

real	0m17.169s
user	0m16.724s
sys	0m0.324s
$ time inkttt -f 152x152-clones-unlinked-2b.svg --verb=DialogXMLEditor --verb=FileClose

real	10m9.303s
user	10m8.126s
sys	0m0.793s


### 152x152-16-groups-2c.svg
### same amount of objects, separated into 16 groups with max. 1444 objects each:

$ time inkscape -f 152x152-16-groups-2c.svg --verb=FileClose

real	0m16.972s
user	0m16.459s
sys	0m0.381s
$ time inkscape -f 152x152-16-groups-2c.svg --verb=DialogXMLEditor --verb=FileClose

real	0m17.706s
user	0m17.148s
sys	0m0.383s
$ time inkttt -f 152x152-16-groups-2c.svg --verb=FileClose

real	0m17.353s
user	0m16.906s
sys	0m0.325s
$ time inkttt -f 152x152-16-groups-2c.svg --verb=DialogXMLEditor --verb=FileClose

real	1m19.241s
user	1m18.681s
sys	0m0.407s
$