The CData provider can cache retrieved data in a local file or an external database depending on your connection string configuration. It can cache not only the data but also the data source tables metadata information.
When you specify
in your connection string and you also have the Cache Location or Cache Connection and Cache Provider set, the table metadata will also be cached. The next time a connection is made with the same connection string, the metadata will be read from the cache instead of retrieving it from the data source. This is much faster.
However, bear in mind that you will not see any updates to the table's schema definition since you created the cache.
This feature is only applicable for data sources where the CData provider uses dynamically retrieved schema definitions. Those includes SharePoint and Excel.