Handling large datasets in ArcGIS can be a truly painful process. When you are up against a deadline, the seconds spent wasted waiting for ArcGIS to update its display or run a query can be excruciating.
That is until you discover spatial indices! It is like a new world, where querying data is (almost) fun, and not an reason to go and make a cup of tea. Plus it is incredibly simple.
To apply a spatial index, firstly find your troublesome dataset in Catalog. Right-click and go to Properties. Then the Indexes tab. See Spatial Index in the bottom pane of this window and click Add. This will take a few seconds but once in place it will significantly improve the speed of your redrawing and querying.
Having said all this, I’m not sure this will be new to many – but I found this very useful. More information is available from ESRI themselves here.