If you have 8.2, you could use the diagnostic tools to evaluate the time spent executing the webservice. What is probably happening is that the javascript is taking a long time to swap out the new UI for the old UI.
To verify that you could use some of the fancier browser tools like Firebug.
If possible try to minimize the amount of UI that needs to be refreshed.
Regards,
–mark
#MWS-CAF-Task-Engine#webMethods-BPMS#webMethods