GsView 5.0 setup ListView redraw loops cause the setup to be extremely slow

0.4.6RC1 is affected.
The bug is very old, I noted it the first time in my ros 0.4.1rls tests.

When you install GsView 5.0 from rapps, the copy-progress is visualized via a listview.
Seems like there are some heavy redraw loops involved then, because it takes minutes on ros to install that tool and only seconds on windows.
The more the ListView is filled, the more severe the delay becomes.
gsview.webm (that vid shows ros 0.4.6RC1) shows only part of the setup to not bore you to death.

ros generates no log output during that.
ListView? Scrollbars? Win32SS?

Expected result
2k3sp2_Jesus_That_Progress_in_the_listview_runs_quickly_indeed.webm
2k3sp2_CPU_Limited_to_10_percent_in_Vbox__it_proves_that_nothing_should_be_jumping_up_and_down.webm