The base resistor of the transistor with speed-up capacitor
The resistor R2 is there to protect the CD4013 chip. If it is not present, the chip's output transistors will see a very low impedance to ground (through C1) for a short period of time when they change state and this could damage the chip.

To calculate a safe value, look at the maximum output current from the CD4013 and size R2 so that this is not exceeded when C1 is a short circuit.

As other commenters have stated, a relay is so slow to respond that a speed up capacitor won't have any appreciable affect on the performance of the circuit.