Running Xwin in 8 bit depth

[salahz@look.ca]

Hello,

I have succeded to run Xwin on a thin client Terminal
connected to a Windows NT 4 Terminal Server Edition (RDP protocol).
Now i noticed the following behaviour, and was wondering
if there is a way to avoid it:
Situation 1: On Terminal or PC (set to 256 Colors)
- XWin :0 -query host
  i get the logon in about three minutes.

- XWin :0 -query host -fullscreen
  i get the logon in 20 seconds but the whole screen is black,
  except the cursor, i can however login but the screen is ugly (black and
white).
  Note: i tried -engine 1 2 4


Situation 2:
On the same PC Set to (65536 Colors)
XWin :0 -query host
I get the logon in about 20 seconds.
I could not test it on a terminal Max resolution 256 Colors.

It seems that the fact that the depth is 8 bits is slowing the logon
display (three minutes is an eternity for some users) but once in,
the application displays at normal rate.

Any help is greatly appreciated,

Thank you,

Salah.