If your API is fast with seed data but slows down in production, EF Core is rarely the root cause. It is usually the amplifier.
Most teams do not have one catastrophic query. They have many small query-shape decisions that compound into high P95 latency, lock pressure, and unnecessary database scale-up.
This article is a practical field guide to 10 EF Core performance mistakes I keep seeing in production .NET APIs, and the fixes that usually move the needle first.
In this post
Why this matters in production
