Check my little project - hangs with "Not Responding"

Hi guys.

Been amusing myself with a little project. A Hash Checksum verifier.

If I check a .svf file, which is small the app works a treat but if I input a large .iso file the app hangs with "Not Responding" for a wee while then gives the results I wish.

I don't know what I am doing wrong. Was hoping somebody could look at it and give me a clue

Cheers..

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