MGNLPN-233, we were wrapping nodes with PersonalizationNodeWrapper only if the given page had a variant. This resulted in some issues (e.g. displaying the original titles in navigation when viewing it on pages without variant). MGNLPN-233 fixed this issue, but the performance was severely affected.
The optional switch wrapOnlyPersonalizedNodes is therefore added to /server/filters/cms/variantResolver. (default is false)