Omfg
I think I finally understood #Python, #Lutris and #GTK sufficiently, and my brain decided to do one of these super rare happy chemical flushes.
Fucking Poggies.
The speed result is completely inaccurate (turns out the existing Downloader class doesn't wait long enough if all you care is for the very first measurement), but right now I'm just happy it updates the text accordingly every time.
#coding