Navmesh recastnavmesh playground speed vs local

with the example: https://www.babylonjs-playground.com/#HFY257#4 the navmesh creates in around 7ms. when i download this exact example i have to add
preview.babylonjs.com/recast.js” for it to work and when i do the navmesh creates in 500 - 600 ms. what am i doing wrong??

Is it faster the second time a navmesh gets created?

nope, refreshing the window roughly the same amount of time(500-600ms) where as in the playground 6-7ms. when i replay there(not refresh) execution time goes down to 2-3ms(playground only)

also the playground doesnt use recast.js? im guessing this is the execution time issue. ifnot recast then?

so i created this in nodejs, it seems to be an initial one time cost for load. re-creating the navmesh using an interval timer with randomly generated meshes i am able to get 1-2ms creation time… initial time for some reason is 600ms .