it's the number of pixels that matters. so yes. U need more powerful GPU to get the same fps as before. else your fps will be lower about 20%. with your setup, U won't find a problem(60 fps is no challenge for your rig). but be aware that it's not very funny in all games. the game should support 21x9 aspect ratio and if it doesn't, it would be sth like these:
http://i.imgur.com/KK9SllY.jpg
http://www.techspot.com/articles-info/1103/images/2015-12-04-thumb-3.jpg
most games support this 21x9 aspect ratio and newer games should support that.
one more thing, I had some deep research and the result is 144hz monitors make a noticeable difference in gaming. so if U do some gaming, keep an eye for 144hz monitors on market.