Stellarium 0.21.1 gotcha - high CPU use under Windows (solved)

[Zermelo]

Sharing this in case anyone else is experiencing the same problem.

Since upgrading to Stellarium 0.21.1 I've noticed it is very laggy, and thrashes my CPU to the maximum. My laptop is a few years old, but I'd not had the same issues with previous versions.

After a few false trails (and not finding any similar reports online), I realized that the cause was a change in the default parameters that are included when Stellarium is executed - specifically, those related to the graphics rendering (this has also been noticed here).

The Stellarium Windows install creates no fewer than ten launch shortcuts under the Start Menu folder, as well as a desktop icon (if you request it). But I normally launch the program by hitting the Windows key, typing "STEL" in the search bar and hitting "enter", which is usually faster for me than finding an icon. What seems to have changed with 0.21.1 is that the default launch shortcut selected by Windows is the one that invokes "MESA mode". Note that this is not the same mode invoked in the desktop icon created on install (nor for the icon created on the previous install). Launching in this mode appears to tell Stellarium to refrain from using the laptop's GPU, meaning that the CPU is responsible for all the graphics rendering (you can see this in the Windows task manager). It's possible that other hardware configurations may not behave like this with the 0.21.1 install, but if yours does, then try launching it from the icon instead.

Previous Stellarium desktop launch parms: D:\Program Files\Stellarium\stellarium.exe" -platform windows:altgr
0.21.1 desktop launch parms: D:\Program Files\Stellarium\stellarium.exe" --angle-d3d9 -platform windows:altgr
0.21.1 default "Windows search" launch parms: D:\Program Files\Stellarium\stellarium.exe" --mesa-mode -platform windows:altgr

[inFINNity Deck]

I had a similar issue with 0.21.0. In the default Windows-key followed by typing "stel" start-up, it would freeze every half minute for several seconds, having issues with screen rendering. Then I choose several times the alternative "Angle Direct3D 11 mode", which gave no issues, and now Windows remembers that I prefer that version over the default one. Still I would like to change or remove the original one, but seem unable to do so.

In the meanwhile the observatory-pc runs 0.21.1 as that version remembers that I want to connect to the mount ASCOM driver.

Nicolàs