How to optimize

Rule of thumb for optimization

Mind your actual resolution

When searching for a great background image it is easy to forget about the real size of the file. To make your machine calculate less when rendering your awesome new picture make sure to resize it to fit your screen. On high end systems this may not make a big difference but Sugar is written with low end equipment in mind and using a 9200x6400 picture on a machine with a screen of 1366x768 and a relatively weak CPU or GPU is unnecessary and will make a noticable difference when starting your login manager.

Also help Sugar speed up on calculations it needs to make to lay out the interface by adjusting ScreenWidth= and ScreenHeight= to your actual screen resolution. This can also help prevent bad proportions, distortions or bad placement of elements.

Don't get crazy with fonts

Custom fonts can be nice (or not) but may also be actually really big in size. Things like scattered or textured fonts (often from free resources) may consist of an incredibly huge amount of vectors which need to be calculated by your computer. This can slow down your system and make for a horrible log-in experience.

Go slowly and test

When changing any variable you will want to see the effect it has on your login screen. Most people would save the file, save everything else and log out just to log right back in to then change something else and to do the very same over and over again. You can be smarter than this by testing your theme from the command line:

$ sudo sddm-greeter --test-mode --theme /usr/share/sddm/themes/sugar-light