Many issues related to incorporating real-time spatial information within Geographic Information Systems (GIS) need to be investigated. It can be established that the concept of real-time in relation to the input, analysis, display, and output of complex spatial information depends directly on specific user applications. This dependency has been evident throughout the Naval Research Laboratory's development of a real-time GIS for hydrographic surveys. This paper contrasts the issues and requirements observed for this application with those of vector moving-map displays for high-speed aeronautical applications. It also attempts to quantify the influence of various factors and impacts affecting real-time response to specialised applications like vector moving-map displays.