Q:

how to reduce the delay in action support?

There is custom controller with more than 60 fields and getter/setter. whenever action support call on onchange of picklist, it takes long time to  display the result.
I noticed that it runs the getter method of the filed which we have used in the 'rendered' attribute. (for example: rerender ="{!isDisplay}").
any suggestion to avoid this delay?

A:

If you're only changing one thing, wrap the changing element in an apex:actionRegion.  Then only part of the form/page info is sent, and the round trip is faster.
Js remoting will be faster, but if you like to use standard visualforce and use less code, actionRegion helps a lot.

