I think there’s still a chance that the final parameters aren’t decided. As for being optimised, it would be a mistake to create an Equihash solver that was incapable of or difficult to adapt to different parameters.
Zcash wants the PoW to have a memory footprint close to 1GB,
but feared the originally planned (144,5) taking too long to solve.
They thought (200,9) should take over 500MB, but didn’t foresee (and neither did the Equihash authors) the recent solvers that can use as little as 128MB to solve (200,9) with no slowdown.
Realizing that (144,5) doesn’t take that long to solve after all (mere seconds), they strongly consider a return to these parameters after launch.
Note that because our desired mining goals are best-aligned with general-purpose hardware, a hard-fork to different parameters is a much easier change than from a PoW that has a lot of sunk cost in specific mining hardware (like Bitcoin’s double-SHA256).