Help on WebTerminal performance

Running WebTerminal from OpenExchange over HTTPS could be a very secure access method for remote developers.
So I was asked to compare it to other access tools.

One of the tests was display speed.  So from the command prompt, I did a simple ZWRITE ^SYS
I started it in parallel:  WebTerminal, IRISterminal, Putty
- PuTTY completed first, though started last
- IRISterminal took some time longer but ended somewhat later
- WebTerminal first chopped the output but was then incredibly slow. 

So I feel I missed some important settings in installation.
I just couldn't find any related hint in the docs. (BuerSizes, Switches, ...) 
What are your suggestions?