I already posted a suggestion about that in another thread, but I will repeat it here, too:
There must be an icon or a tick-box to quickly toggle the selection highlight. Extremely useful while working with dense 3d mesh models and point cloud data. The toggle must be visible all the time and the user must be able to switch it with a single mouse click, so the best locations is ether in the the Status bar at the bottom (next to “Filter”), or on the left side of the “Select all” icon, or on the right side of the “Properties” icon located below the Command line.
It will be even better to be able to apply the highlight toggle to a certain type of geometry, such like meshes only, while the rest ones will still take advantage of the default highlight.