It seems like the answer to your question is "No". (I tested this out in a WebDirect app)
Thanks, that sounds completely reasonable.
For a client where processing happens at the clients end (FileMaker Pro and FileMaker Go), the object with conditional visibility will be part rendered to assess the calculation. If the calculation result is false, no further rendering occurs.
With FileMaker WebDirect, the performance will be better from the browser end. This is because all processing happens on the server. So the only data sent to the browser is the resolved layout. So conditional visibility certainly would not cause 'chatter'.
Much clearer. Thank you both.