Guild Wars 2

I am in a closed beta test of another MMO and I saw they use there “Dynamic Resolution system” which allows the game to reduce dynamically its resolution in big mob fights to increase performance. Every player has the option to set out the minimum resolution but as default it is set to 30 fps.
I think this would be a good idea for A-Net to try out too.

GW2 isn’t designed in a way that that would make a difference. Test it out yourself and see if a resolution change would be useful. Also, most of us are using LCD screens that really don’t like being outside of native resolution and running in lower resolutions in desktop mode kinda defeats the purpose that idea proposes.
Since GW2 isn’t a client-side processing game, the performance increase you think you’ll get will only happen if they open the data flood gates and you increase your network bandwidth, install SSD’s for instant asset loading, and overclock your processor to handle the massive amount of character positioning data it has to help your graphics card render.