High Performance loss with SharedFolders

[Soulatial]

I have an apache/xampp System with PHP free chat running in a virtualized win xp on an win xp host.
When I start the xampp system from the shared folder I get a reaction time of about 5000 ms (php free chat shows me that), also I have a periodically high (=100 %) cpu usage on the host.
When I copy the xampp system directly into my virtual xp and run it from there the reaction time is only 700 ms. Thats a lot of better and in addition I never have 100 % CPU usage.

When started from the shared folders, the "VBox Tray" Application also takes a high percentage of the CPU power.
How comes that high performance loss and why does "VBox Tray" steal so much CPU time?

Thanks for your help.

[mpack]

What kind of shared folders? Guest Additions has a shared folders feature, or you could be using a network share. I've noticed what I think is a big performance drop with the GA-SF feature in 3.x, but a network share is still pretty fast, especially if I'm using "Host Only Network" mode (I add a second NIC if necessary to get this), since it means I map the share to a drive letter (in my Windows guest) using a static IP address. There may be better ways, but that works for me.

[Soulatial]

I meant the shared folders feature of the guest additions.

A normaly networkshare with bridged network wasn't fast as well. I'll try with a host only adapter network share.

But still there should be done a lot of speed improvements.