A stand-alone table in your document is using the NetCDF data format as a data source, which can perform slowly in some situations.
Solution
Convert your data source to a file geodatabase or enterprise geodatabase. See Migrating to the file geodatabasefor more information.
More information
NetCDF is an open standard for the sharing of array-based data and is primarily used in the climatology, meteorology, and oceanography disciplines. NetCDF is a flexible format that is well-suited for the distribution of multidimensional data sources, but it is not optimized for draw performance. For instance, NetCDF data drawn as a raster dataset does not draw via pyramids. When NetCDF data is drawn as a vector data source, the vector data does not have a spatial index, resulting in decreased performance. For faster performance, consider converting your data to a spatial data source such as a file geodatabase or enterprise geodatabase.