The body runs more efficiently on glucose when measured in terms of oxygen consumption. That's why very few elite endurance athletes eat ketogenic diets. Their performance is limited by how much oxygen they can metabolize.
It’s anerobic activity (sprinting or bodybuilding/Olympic lifting) where there may be a slight detriment in performance.
I’ve run marathons in both ketosis and running on glucose. I won’t go there because it’s anecdotal but marathoners, body builders and Olympic style lifters are not the norm and have different requirements especially competing for records. No doubt it’s one thing to live in a natural state of ketosis and treat yourself to a performance boost with some fruit when you are about to burn any glucose than what almost the entire modern world does and spikes their insulin levels all day every day and their body/cells basically not even familiar with how to use ketones as a fuel.