The biggest productivity boost for me happened after I started using a Tiling WM (i3). I started out of necessity when I felt I have reached the maximum optimization with XFCE DE. I just didn't want to organize my windows manually again. Now browsers are all in 1st workspace. Text editors are all in 2nd. 4th is for chat apps. 6th for reading and documents like excel, pdf etc, 8 for image editing like GIMP, KRITA, Ink…
Not using a tiling WM, but especially on small notebooks I'm so desperate for compact decorations and a global Mac-like menu that I've even prolonged life of my old XPS 13 w/ Ubuntu 16.04 using Ubuntu Advantage/extended security maintenance (their old gnome2-based desktop with Unity). At least there's some hope using KDE Plasma eg. [1]. [1]: https://www.dedoimedo.com/computers/plasma-look-like-ubuntu-...
KWin will also let you set how much (or how little) window decorations you want if at all. I'm very happy with it.