I think I may have requested this before but...

Given the power of modern machines, a realtime refresh of the Web Preview should be possible, so you can see the output as it's being typed.

To make this real-time refresh useful though, it would need to preserve the current position in the web peview, rather than always jumping back to the start on every refresh. This way, you can scroll the relevant part you're editing into view, and continue editing, while seeing what it would look like in the preview.