Inserting 10,000 features into a feature class is slower with the standalone CoreHost ArcGIS Pro SDK app than with an equivalent ArcObjects Engine application.
Duplicate of BUG-000126871: Tell the client to use the new InsertCursor class added at Pro 2.6.
https://github.com/esri/arcgis-pro-sdk/wiki/ProConcepts-Geodatabase#editing-with-insert-cursors