Today I stumbled upon this reddit-article.
It speaks about using the modesetting driver shipped with xorg instead of the xf86-video-intel driver. I did a benchmark with the xf86-video-intel and the modesetting driver to see which performs better in order to decide if I will drop xf86-video-intel. Here are the results:
Unigine-valley Basic preset @xf86-video-intel:
| FPS: | 14.4 |
| Score: | 604 |
| Min FPS: | 8.2 |
| Max FPS: | 33.1 |
Unigine-valley Basic preset @modesetting:
| FPS: | 23.5 |
| Score: | 984 |
| Min FPS: | 11.8 |
| Max FPS: | 40.3 |
It doesn't really matter what hardware I'm using, all that matters is that the situation improved. But for reference: Intel HD Graphics 5500.
So my choice is simple, I'm ditching xf86-video-intel in favor of using modesetting, which was already installed on my system together with xorg-server.
because of the switch to modesetting driver the xbacklight utility does no longer work. Using a xorg config file with the Backlight option set to intel_backlight also does not work as a workaround. So I installed light-git (from the AUR) which allows me to control my laptop backlight once again.