Capturing Signature through Citrix client via Mac client is so slow

[19972003]

Anyone has any idea how I can fix the slowness of capturing signature via Mac client?

Environment:

OS: Win2003
Application: Citrix 4.0
TT1500 is installed

Issue: when the Mac client launches citrix connection and tries to grab the signature via the citrix session, the image shows so slow.

Mac client setup:
Latest Keyspan USB driver installed with Com port mapped;

TT1500-serial cable with power adapter-Keyspan USB adapter-USB cable-Mac client

I can get capturing signature image show up immediately through windows client.

Thoughts?

TIA