5/6/2014 (early am testing)
run against my C:\ (~137.6GB, ~870,000 items) - size on disk

"vanilla" WinDirStat
12:04:30
12:07:00

rendering UNTILL 12:09:20!


altWinDirStat
12:18:00
12:21:40

rendering UNTILL 12:24:10


(early AFTERNOON testing)
5/6/2014
generated junk dir:
----------------------------------
running against C:\, (~140GB, ~1,600,000 items)

"vanilla" WinDirStat
 12:41:00 (UI thread locks a few times while scanning)
~12:44:30 (whoops, looked away!)

rendering UNTIL ~~01:48:xx (had to use the bathroom!)
rendering after clicking takes a good minute
clicking on a rectangle in the test_junk_dir takes....don't even ask


altWinDirStat
 01:59:00
~02:03:00 (shit stopped looking)

rendering UNTIL...god knows



(internal timing implemented. now displays searching & drawing time)
5/15/2014
---------------------
running against C:\, (~143GB, ~1,600,000 items)


altWinDirStat, release build, running under performance wizard  
(~6:40PMish) scanning whole C:\ much faster, but rendering horribly slowly. I went to the store, came back, went out to get a slice of pizza, (and came back) while waiting!
Profiling revealed that MOST of that time was spent in qsort!