When both tables are open in the data editor - parent and child - continuous movement of the cursor row along the parent table causes unnecessary queries of the child table for each row in the parent table.

This leads to an increased load on the server in the case of a client-server configuration, and in the case of a local DB there is no need to load the processor in vain.
I think it makes sense to execute a query to a related table with a timer delay, i.e., only when the cursor along the parent table has stopped moving. In my programs, I do this - a query by timer after ~0.3 sec.

This is especially relevant in our difficult times, when all progressive humanity is actively fighting for energy conservation (as well as with global warming / cooling, pandemics / stomach cramps and other misfortunes on schedule).
I think it makes sense to implement this - and Greta Thunberg will be happy!