EF Core performance checklist — Entity Framework (EF6 & EF Core)

13. EF Core performance checklist

Advanced★ Must knowLesson 13 of 15

Project with Select — fetch only needed columns.
AsNoTracking for read-only queries.
Avoid N+1 — no lazy loading in loops; Include or projection.
AsSplitQuery for multiple collection includes (cartesian explosion).
Paginate; never load whole tables.
Indexes for filters/joins/order-bys (HasIndex).
ExecuteUpdate/ExecuteDelete for set-based changes.
AddDbContextPool and compiled queries (EF.CompileAsyncQuery) for hot paths.
Keep contexts short-lived; don't track thousands of entities (DetectChanges cost).
Check generated SQL (ToQueryString, logging) and execution plans; drop to Dapper/raw SQL for complex reports.
Avoid client-side ToList() before Where.
Use AnyAsync for existence, CountAsync only when needed.

csharp

private static readonly Func<AppDbContext, int, Task<Product?>> GetById =
    EF.CompileAsyncQuery((AppDbContext db, int id) => db.Products.FirstOrDefault(p => p.Id == id));