Progress bars for file in the Downloads Details tabs freeze Tribler

[ichorid]

A forum user reported that on slower machines drawing progress bars for a torrent of a dozen files makes Tribler unresponsive. That is confirmed on my developer machine with some testing. The problem is, we're using QTreeWidget, which becomes super-slow when replacing any column with a widget (such as a progress bar). To solve the problem, we must refactor the Details tab to use QT's Model-View-Delegate pattern.

[drew2a]

I'm wondering whether #7705 fixed this issue, @qstokkink?

[qstokkink]

The issue, as reported, is indeed now fixed.

We could still optimize the piece retrieval further to also make the piece information on the "main" details tab more efficient. However, that's probably best left to a separate "enhancement" issue instead of a "bug".