Show a Warning as soon as Knack forgets how to count

Knack should show a warning/send a mail to the admin when a formula field will not be calculated anymore for "performance reasons". We have about 40 existing fields in our app which are affected by it and are therefore only calculated by chance and your support folks regularly tried to fix.

The reason was recently discovered at the bottom of a support article:

In order to optimize performance, formula fields (eg. Sums, Counts, etc.) which <strong>include filters</strong>
 are currently limited to processing 10,000 records. A formula field 
that includes a filter that tries to calculate a connected object with 
more records than this will display inconsistent results.