Bad performance with Objects dialog and Undo History dialog open

Steps to reproduce:

1. Working with Objects and/or History dialogs open slows down certain operations, like undo, applying extensions (like perspective or inset), grouping, ungrouping.
2. Closing those dialogs won't improve the performance unless Inkscape is restarted.
3. Working with those dialogs closed is not a guarantee for the undo command. Undo happened to take about an hour after an inset operation on 8000 or 400 objects as well.

Inkscape Version and Operating System:

Inkscape-2b71d25-x86_64.AppImage Inkscape 0.92.4 5da689c313, 2019-01-14

Operating System: Gentoo Linux KDE Plasma Version: 5.17.4 KDE Frameworks Version: 5.65.0 Qt Version: 5.12.5 Kernel Version: 5.3.0-sabayon OS Type: 64-bit Processors: 8 × Intel:registered: Core:tm: i7 CPU 920 @ 2.67GHz Memory: 23,5 GiB of RAM