I have this problem too.
About a year ago, I tried the blocks demo in VR, and was absolutely blown away by the accuracy and responsiveness - I was a beta tester of an early version of the device, and things had improved leaps and bounds since then.
I recently found my old beta version device and connected it to Oculus, and the tracking was very bad - jittery hands, unable to pick up or release objects in the blocks demo, objects randomly stick to the hands, fingers and whole hands popping in and out.
I figured maybe this old beta device was not as accurate or didn't support current drivers very well, so I ordered a new device, which just arrived. Sadly, the tracking is every bit as bad, perhaps even worse.
Have tried calibrating, to no avail - and it says the calibration is good anyway. Everything lights up green in the control panel.
I'm on an extremely high-end system, and the diagnostics tool consistently shows data and frame rates around 100-115 FPS, and the room is very well lit.
I noticed in the diagnostics tool that there are invisible (infrared?) emitters of some sort on the Oculus controllers, to which the Leap cameras are clearly extremely sensitive, and one thing that helped a lot, was to make sure the Oculus controllers aren't in the Leap's field of view.
It's still not as good as I recall it being in the past though.
I suspect there may be other devices in the room creating interference - for example, this office space has a motion detector that switches the lights on and off automatically, perhaps this is also emitting some kind of optical signal that interferes with the Leap??