There will allways be lag on the internet, but bad code is often the reason why it's so noticeable.
We will allways have some small delays on boats positions, wich means your opponent is a few meter further ahead of what he appears to be. We can live with that. But what is not necessary is to slow the client boats down due to lag to the host. The speed/acceleration of the boat should be calculated from the wind information your local pc only! In the present version of vsk, it's far from the case... Your boats speed/acceleration is calculated with wind information from the hosting boat, which is not in accordance with the wind you see on your screen.
This is the reason why the Maria Island course is the best lagwise, and waiheekee is the worst. The wind is much more stable at the Maria Island, while it's full of strong gusts with variable wind direction at waiheekee. This means you slow down when you sail onto a gust which only appears on the hosting machine (at that time).