FIRST Guidelines, Tips, and Good Practices page 5 has a table with all the CIM speeds. The term "peak load" is kind of ambiguous, you should probably go for "design load", which is shown as "normal load" in that table as 4320 RPM. But before you run off and determine robot speed based on that, remember that the motor could care less what speed you want it to run at; it is going to run at the speed that corresponds to the load (torque) demand you put on it. You design to an applied load and the speed is a fall out, not the other way around.