hook Mechanism will slow in server 2008

[stephen_li]

is ultravnc use the hook mode in window server 2008? i found from the internet that " VNC will be slow if the screen capture method is set to os hooks on Vista and 2008, especially the 64 bit versions.
Selecting "poll screen" for changes makes a big difference."

if ultravnc do not use hook Mechanism,i want known why the hook mode will be slow in server 2008
if ultravnc use the hook Mechanism,i want to known the trick?
thanks

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