In NetFlow table,

• Under Query Options, set limit to 1000.
• Set time range to "Last 15 minutes" or longer.
• For the filter, select "Common IP".  Enter any IP address like 1.1.1.1.

This will almost always results in a popup that says "Query is slow" (see attachment).  This also happens with filter "Common Port", although it occurs more readily when there are only a few rows with that port value.  If you set the time range much longer, it returns an error message (see attachment).