I've had another look this am. The long delay only happens when I run in debug mode.

It didn't seem to be last night but it is reading the clipboard contents (btw if clipboard is empty it throws a null pointer exception) and is converting the text.

The setting of the new clipboard contents is random though. It can leave the contents unchanged, empty the clipboard or update correctly.

I'll try to have another play another day and see if I can work it out.