Light probe visualization carries a huge cost even when not rendering due to disabled gizmo settings, when the scene has tens of thousands of light probes having light probe visualization settings enabled comes with a 100-200 ms cost on a large i7,even if lightprobe gizmo drawing is disabled, this becomes kind of a trap as it is easy to forget you enabled that mode in the lighting panel and will continue to pay the cost for something that is not even rendered.