Hello,
I recently had the same experience. I'm using a Focusrite Scarlett 2i2 USB Audio Interface. Using Cakewalk in ASIO mode, the latency while tracking is very very low. Using the Mix Editor, I would approximate the latency at 500 ms. This is insanely high. I believe it is deeply architectural as the browser is limited to using MME, and may well be introducing other latencies on top of that. So for me it was a bust.