A cryocooling system includes a compressor, a refrigerator, and a controller, which is communicatively coupled to the compressor and the refrigerator. The compressor is configured to be driven at a drive frequency. The refrigerator is coupled to the compressor via a first fluid path and includes a cold heat exchanger, an output, a reservoir, and a flow resistor. The flow resistor controls fluid flow along a second fluid path between the output and the reservoir. The controller optimizes a rate of cooling of the cold heat exchanger by adjusting both a drive frequency of the compressor and a resistance of the flow resistor along the second fluid path.