Soldato
Did you set it as the global setting and use adaptive not just vsync on in nvidia panel. Dont use it using nvidia inspector as i think it doesnt work too well that way i dunno.
One thing i tried to do which failed miserably is try to avoid vsync using frame rate limiter in nvidia panel. It really messes up the game if you avoid any form of vsync its like its a requirement to have vsync on in this game. I thought setting the fps to 58 would fix it and never tear as never go over 60 but ingame it did go over 58 as i set it went to 60 and i thought EH! So that method failed so the adaptive vsync is best i can come up with to avoid the 30fps drops when your near a little over 60fps due to vsync so far it works well it doesnt drop sharply now so less stutters as no more sharp drops.
Anyhow just sharing what i tried in general as that 30fps when you get it is not pleasent.
Use rivatuner statistics server to limit fps? I'll try when I get home to lock mine to 30fps and try running this in 4k scaled down to 1080p to see what results I get.
Probably a slide show as my poor 780 eats it's self.