Hi @jef-n, I released a experimental coomit, for show the problem: this 'OGR_G_SetPoint' is a terrible bottleneck because of it does a realloc of one point each new point.

The only solution that I see is disable the simplification on ogr provider side when __cplusplus is not enabled, I can do it because the provider capabalities indicates if it can do simplification

What do you think ?