How do I speed up or slow down the collapsing or expanding of an CollapsiblePanelExtender

How would I go about speeding up or slowing down the collapsing or expanding of a CollapsiblePanelExtender.

that i guess would not be possible becoz the expanding mainly depends on how fast the content come from the server,basically depending on the internet conection.the next(after the first) expand could be faster if caching of the content is done.