The Resource Planning portlets takes a long time to return data.
Release: Clarity
Component: Resource Planning Portlets
It is normal for Resource Planning portlets to take up to 15 seconds to populate as it depends on the data being fetched.
Always enforce a filter as users can inadvertently request a large amount amount of data, creating a performance hit.
For each portlet configured, the following option to "Do not show results before I filter" can be set.