something deeper than notepad has a big performance glitch

This is a ticket (just) about execution performance, but this sucks regularly, so:

It's broken since 0.4.0 at least (or since forever?).
I report it against 0.4.8-dev-664-gf463ebe.
VBox 4.3.40.

Steps to reproduce:
-Double-Click C:\reactos\readme.txt (or any other arbitraty txt-file)
-It will open up properly in notepad.exe, but it will take very much time before the text is actually rendered to completion (slowness)

Only thing that is logged then, is

fixme:(../dll/win32/shell32/shlexec.cpp:1804) flags ignored: 0x00000004

CFSFolder.cpp:735: Unexpected failure 80004002.

CDrivesFolder.cpp:506: Unexpected failure 80004002.

CRegFolder.cpp:422: Unexpected failure 80004002.

But the logging is not the reason for the slowdown.

I verified (all tests done in same virtualization):
-our notepad run in W2K3_SP2 is fast
-W2K3_SP2-notepad run on W2K3_SP2 is fast
-W2K3_SP2-notepad run on ros is slow
-our notepad run on ros is slow

I conclude: It is not our notepad-binary that sucks, but either text-rendering, scroll-bar-rendering or file-IO that is slow.
I suspect it may be related to the scrollbars.
Eventually related: CORE-13631 or CORE-11561.