I dont understand, why the core has such a bad pathfinding.
Great pathfinding -> high CPU load and low frame rate
Poor pathfinding -> reduced CPU load and higher framerate
Vanilla has attempted to increase performance in pathfinding, but broke it in A17. They claim to have fixed it in A18 (now B18) and while it's better, when it comes to long distance travel, it's still worse than this patch.
The real solution would be to get pathfinding done right, order the route and then let another thread plan it. That way even though the CPU load itself is not lowered, it is spread across multiple CPU cores.