ArcGIS Server Application

The most recent version of ArcGIS Server is 9.3.1. It help building caches faster than before. If possible, using cache if possible, it will help to load your pages faster. Also try to have all your layers in the same coordinate system. It will make the map loading time shorter. Furthermore, do not show high-detailed layers (like parcels and local roads) in small scale. Testing your application in both Internet Explorer and Firefox. Also testing your application in different version of the same browser.