Minimize on close behavior made optional.
See the Changelog for list of features and fixes currently only available in the nightly builds.
You raise a very good point. The process of updating the progress bar is relatively intensive for something that may be happening hundreds of times a second, if there are a lot of uploads and/or downloads in progress. If I were to try different possible improvements, would you be able to try them out and see if they make a difference?
I took your advice and limited the length of time each download and upload updates their progress. It's currently set to half a second, but I might add a setting later. Let me know if you notice a difference: