I have a couple of cheapish laptops that I want to use as slaves to do distributed recording using three Kinect 2 cams. The frame drops on the laptops are pretty extreme though (down to ~13) and I'm wondering what the best way to get that up to the necessary minimum is. Does anyone have experience using a multiple Kinect 2 system?

Maybe your cheapish laptops do not satisfy Kinect 2 requirements. New Kinect SDK uses video card extensively. Also, there may be issues with some USB 3.0 controllers.
Run Kinect Configuration Verifier tool on your laptops and see what it outputs.

I've got the fps working at a reasonable level now, but i'm having major issues with calibrating the Kinect v2.0s using a maglite. There are a ton of misdetects happening, is this more common with Kinect 2 than the original Kinect?

EDIT: I spoke too soon. The Configuration Verifier is giving me a (!) for the USB Controller: "Supported USB 3.0 port detected with unknown bandwidth. Kinect may or may not be compatible with your hardware."

The Verify Kinect Depth and Color Streams pane is also flickering a lot. It seems to be losing track of the kinect constantly. Is this a USB issue? If yes, what are the best fixes to try?

If you get stable frame rate in iPi Recorder without much frame drops (10 per minute is an acceptable number) then I think you should not worry about the verifier.
If not - try other USB 3.0 ports or get another laptop having Intel or NEC/Renesas USB 3.0 controller.

Assuming the device is working OK, the problem with misdetects is generally caused by two reasons:

• Light is often occluded by a person holding it. Solution: practice with your motions during a calibration paying attention that the light is visible to all cameras at most times.
• Light spot is too big or too small. Try running calibration with different settings for the marker size. You can find it in Manual Calibration Adjustments expander.