Threads.@threads is still consider a bit experimental and there are a few performance pitfalls that one can stumble into. I talked about this for a bit in http://slides.com/valentinchuravy/julia-parallelism, but if you still have issues after reading that feel free to reach out on https://discourse.julialang.org and we will figure out what is going on.
Very technical presentation, but it contains nuggets of that I can't wait to try once I get home! Do you have a blog that lays this out in a way that is aimed at the general Julia programmer?