Hi - ignoring just the performance issues - which are major, you would also need to solve the driver issues.
As an alternative, why don't you use a different architecture - e.g. plug the leap into a PC, which gets all the data into NodeJS - then use socket.io to push the data to a browser based client on the windows phone. And - if this doesn't work, you can still run on a PC.
You would need to test out the latency to see if this made sense - the delay in the network might be too great, depending on what your application is - remote flying a drone is unlikely to work.
I would also recommend that you try to let the PC do all the 'heavy lifting', i.e. let the PC pass on gestures, not try to identify them on mobile.
If you're .NET based, you could go with C# PC hosting instead.
Hope this helps