I found this over @ XDA Developers but this replaces your webview.dll file with an older version and seems to fix the slow scrolling issue you see when loading large page in PIE.
So far it's working ok for me, and I tested this with a large page from Wikipedia and it seems to scroll much faster and smoother with no noticeable bugs or anything running Helmi_C's latest WM6 Kitchen on my Apache.
What you need to do is replace your orginal webview.dll file with the attached one in the Windows directory.
More information here:
http://forum.xda-developers.com/showthread.php?t=337521
Edit: I have also attached a cab file.
** I would backup your old webview.dll file before replacing it **
1st file is the zipped up .dll
2nd file is a cab instsaller for it if you perfer cabs.