On most of my ajax calls nearly 50% of overall time are spent in phase render response. If I execute an ajax command and just rerender one outputTextTag then nearly 50-100 millis are spent in phase render response (depending on the machine). This seems to be very much for just rerendering one field and is therefore the first candidate for tuning.
Is the jsf whole component tree evaluated although I specify only some components via reRender attribute? Are there any best practices or tips how to speed this up?