Check the event viewer for any sort of crash report, or what errors it gave right before the crash. I would also try resetting the "manage 3d settings" in the nvidia control panel. Also make sure the limit fps is off in the nvidia panel, since i've seen problems with warframe and that setting in the past.
This is not just a bug in the forge, its a bug across the entire Ui system since the railjack patch. Its like the entire Ui system is loading something and the game hitches whenever anything switches in the menu's like forge or the arsenal. When switching between builds/appearane in the arsenal its most noticable especially if you have 6 different builds or fashions and have different helminth skills on the different builds. If you start switching between them you can basically cause the entire game to start having 3second freezes with just a few clicks back and forth. And this is with a good computer, i would imagine slower computers or when this system rolls out to console its going to completely break something.