To view at a glance the completion and performance of the current file transfer operation

I suggest adding a visual histograph like the default windows dialog

This would also help new users get accustomed to using ultracopier via seeing this familiar UI design element

I suggest making the Y axis autoscaling to keep it relevant
(But maybe with a checkbox to stop the scaling ?)

In windows the X axis is the % of completion, however this can be misleading as the slower it goes, the slower it will fill up.
What I mean is that this does not represent time so far and time versus performance (especially relevant if the copy is happenning over a congestion network) It might make sense to have another check mark to switch the X axis from completion % to duration