I believe that getBoundingClientRect does not force a layout calculation by itself, it only forces queued recalculations to happen synchronously. So calling i

I believe that getBoundingClientRect does not force a layout calculation by itself, it only forces queued recalculations to happen synchronously. So calling it 100 times in a loop should be fast, but calling it 100 times in a loot that also updates the DOM should be cripplingly slow.