I'm having some difficulty parsing your question. It sounds like you're saying that viewing these directories from Explorer on a Windows XP client computer, which, presumably, are filled with lots and lots of small files, is causing that Explorer process on the Windows XP client to "hang". It sounds like you're saying that looking at these directories via Explorer on the server computer works fine. I think you're speculating that a shell extension on the client is causing the "hang". I don't know what this "Cleaner" that you mention is.
While it's certainly possible that a shell extension is causing things to slow up, my guess is that you're just seeing the general "suckiness" of the SMB protocol and latency, multiplied by the number of files in those directories. Even over a LAN-speed connection, with a large number of files SMB can be slow. You're seeing Explorer "hang" because there are so many files in those directories, and I doubt that there's any ill-behaved shell extension at play.
Profile sync isn't affected by shell extensions, but it is affected by the behavior of the SMB protocol and the poor performance that happens when copying directories with large numbers of files. That's why your profile sync is running so slow.
I'd recommend deploying a script that cleans out these directories on each logon. If you don't want to flush them entirely you could trim them to the most recent items (25, in the case of these example lines) by doing:
for /f "usebackq skip=25 delims=" %%f in (`dir /od /s /b "%APPDATA%\Microsoft\Office\Recent"`) do del /q "%%f"
for /f "usebackq skip=25 delims=" %%f in (`dir /od /s /b "%HOMEPATH%\Recent"`) do del /q "%%f"