I wouldn't say they're slow. There have been several threads here about upgrading the wheels and feeling no difference, especially when it comes to speed. The main thing I get from wheel upgrades (at least in the "cheaper" range for around $500) is that you get wheels that might be more stable - softer ride with few vibrations and staying trued longer. Still, that likely depends on the rider's heaviness, like around 200lbs or more. So if you're heavy, you might consider upgrading if your wheels need to be trued often and if you have to pay for the service.

I have RS10s as well and will keep them for some time. Once I become fast enough and start racing, I will consider aerodynamic wheels.