The viewer has two types of panels: pre-defined and user-defined. Predefined panels are ready to render before viewer initialises completely, user defined panels are generated on request (usually by a reader clicking on the toolbar),
Load time can be effected depending on the content that is rendered in a user panel. Complex content involving AJAX can be slower than pre-defined panels. Having the user defined panels load on request means the viewer loads quicker initially.
The viewer predefines 6 panels on initialisation:
The Archive panel has been set as user defined panel, rendering when requested by the reader.