becuase the main (GUI) thread freezes. You either have to keep the message pump going by calling DoEvent (not recommended) or create a worker thread and do inter-threading communication. There are plenty of tutorials in the forum
Thanks
I have added parallel fork, but still no use. it is taking same time to execute and ui still hangs.
Don't mine could you post any of the Perl Thread implementation example link for easy access, as i could not able to find proper one.