Branch for lazy load of clock ([04742d889c]) illustrates the possible win of changeover for single namespace/ensemble to on-demand load, where the performance win is ca. 200 µs/#.
The switch of further subsystems to lazy loading may reduce interpreter creation time to ca. 1000 µs/# what would be almost double as fast than current 8.6 (and tipple as fast than current 9.x).

However, as already said, it'd expect at least (namespace unknown)], and some of the subsystems also further improvements, that may help to load namespace on demand by any access (e. g. on variable or on namespace resolution).