Spatial queries are notoriously slow: Why are spatial SQL queries so much slower than Select By Location?
It sounds like it's possible to optimize the row order of features in a FC to improve spatial query performance:
From @VinceAngelo
[When exporting a feature class, you can develop a workflow to] query in spatial index order, which would optimize created feature order, which should result in improved performance with every query. And if you're going to do that, then you should also optimize your coordinate reference to reduce storage and improve query performance.
https://community.esri.com/t5/data-management-questions/maintain-objectid-values-when-importing-a/m-...
Most of us are unfamiliar with such techniques and how to implement them. Could an OOTB tool be added to ArcGIS Pro that would optimize row order in a feature class for improved spatial query performance?
Related SDO_GEOMETRY post: Optimize row order for improved query/spatial index performance