Things like installing, uninstalling, verifying, etc. take AGES for me, yet on Steam everything is normal. Does this happen to anyone else, and if so, how can I fix it? My Witcher and Xenonauts downloads are messed up and I want to reinstall them but alas it is so slow I cant do shit.

It might be a temporary issue. I know there were other reports.

Did you try using GOG Downloader instead?
https://www.gog.com/downloader

Download the installers with your browser or the GOG Downloader and import the installed games to GOG Galaxy later if you want to.

== IMPORT ALREADY INSTALLED GAMES TO GALAXY ==

1. For GOG games installed using installers from the last few months (so called Galaxy-compatible installers)
Click the "+" button on top of the sidebar and select "scan and import folders" - it will find all compatible games within that folder and add them to the Client.

2. For remaining GOG game INSTALLATIONS
Find the game in the Library (click on the image of the game), then click the More button and select "Manage" -> "Import folder" and point the folder selector into the folder where that game is installed.
Please be aware that Client will accept any folder pointed to and will overwrite files inside it (this can for example wipe some mods or damage other apps in case of pointing to a wrong folder) and will update the game to the newest version (current default language English).