Which rate should we call spinOnce()

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I'm using Qt GUI and a timer in a slot to call spinOnce() periodically. I would like to ask at which rate should I call this function spinOnce()?

At a minimum at the lowest rate you expect messages to come in / events to be scheduled -- if you care about delays.

Ideally at a much higher rate, as delaying processing the event queue (ie: calling spinOnce()) will introduce artificial delays in your event processing.