Some users have asked about the how responsive the user interface is to changing data. The UI, in its current form, is Ajax based, and uses a polling mechanism to request data from the Mango server application. The polling rate is current set at a delay of 5 seconds. By "delay", we mean that there is 5 seconds between the end of a UI refresh and the start of the next (as opposed to, say, the start of the last and the start of the next). (This delay period can easily be made configurable.)
This was a very deliberate design decision, because it takes into account the performance of the many other factors that come into play, including the speed of the user's computer, the performance of the Mango server, and the internet latency between the two. The overall performance that you will experience, then, will be a combination of all of these factors. It will appear better on a local network than from a dial-up connection in another country.
Please note that the performance of the UI and the performance of the data sources are entirely different things. Data sources run as independent processes. Mango maintains a cache of the most recent values from all of its data sources. The UI gets its data from this cache, not by, for example, running a poll of a Modbus network.
Among other things, functionality planned for Mango includes non-browser-based interfaces that can use persistent sockets to deliver near real-time interface updating.