Day: 20 April 2008

Graphical User Interfaces (GUIs) tend to be event driven. A user performs an action and the GUI sends that event to any interested components through a Model-View-Controller mechanism. When the events being sent represent fine grained actions (for example a single field on a form changed, as opposed to coarse grained events like the form being submitted), the performance of the GUI can become an issue. Other examples of when performance of the GUI might become an issue are: when the model in the GUI is large, when the GUI needs to process the data a lot in preparation for displaying it (either client or server side), when the GUI is poorly implemented and duplicate listeners exist meaning that components are refreshed multiple times, unnecessarily. The following strategy has been used to help improve GUI performance. This list is ordered with the easiest / most important tasks (least effort, best improvement) at the top: ensure a clean MVC implementation, without duplicate listeners, add data caches, optimise caches (e.g. they hold more than one object graph), optimise refreshing of non-active elements. 1) Clean MVC Implementation First of all, read the MVC article on this blog. Then, using a profiler or debugger follow your controller as it fires model change events. Are any model listeners fired more than once for any reason? If they are, it is less than optimal and you need to first look for mistakes in the programming logic. If there really is a good reason that the event…

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