What processor are you running and how much RAM do you have?
I can get RON down to 1 frame per second(yes, singular frame for those reading who haven't played 🙂 ) if I set the game up right(Big Huge Map, eight nations, Rush Rules set for Information Age, use the Bantu and build Colossus and max out your population(300), if the other nations do too and you don't have the rig....). I'm running an AXP @2.1GHZ w/512MB RAM- the RAM is my limiting factor. If you turn down some of the details you migh see a slight speed up from freeing up a little bit of RAM, but it isn't due to the vid card.
Vid Card currently is a GF4Ti, but that has no impact on RON's performance. Played it extensively with a GF2, R9500Pro, my current card and even nForce1 integrated graphics in single channel mode(not one of my rigs) and the vid performance was never an issue.
How do you normally play the game? What kind of framerates are you getting now? Under normal conditions I get around 100FPS, obviously that can change significantly though depending on the situation. If you haven't already, enable the framerate counter and let us know what kind of numbers you are seeing and your full system specs.