The occlusion culling may not be the root cause. If you’ve got a SkyLight within your scene using Realtime Capture, it may be that the Cubemap Resolution you have set on that is high enough that it’s taking a significant amount of time to capture that cubemap (this occurs every half a second or so), and the occlusion culling is held up by that causing it to present as occlusion culling hitching when you profile.
If you have one, try reducing the cubemap resolution and seeing whether this alleviates your hitching.
Cheers,
Alan.