Sorry about the "ABC". I haven't had enough sleep

I've just run the same test as you, both with the listbox visible and hidden. I was very careful about form and control sizes for the visible one, so that the paint region was the same. I've taken averages across a number of runs (as this thing is becoming slightly jerking due to encoding mp3s...)

It was all done form a Compiled exe. Not using the debugger.

Results:
Visible:
Vb.Net: 156ms (ranged from 110 - 172, including 5 172s out of ten runs)
vb6: 106ms (range 78 - 165, including 4 94s out of ten runs)

Hidden (NOTE: NOT THE SAME NUMBER OF RUNS!)
Vb.net 528ms little range
vb6 I got bored after about 30seconds...so one run was 38953.