Pretty snappy. All the gnome APIs are written in C. It doesn’t run on node, it runs on gnome-javascript (gjs) which exposes all the C APIs through JavaScript. If you use the Astal wrappers its pretty painless but using the gnome APIs directly in gjs is a little weird since you have to consider things like memory management.
Same. Just don’t become too good at it. Now I have to write whitepapers and participate in speaker panels at conferences. Ugh.