We will look at EF Core 2.0 performance comparing to LINQ2DB - the fastest nowadays ORM. And also Entity Framework 6.
Hardware used: i5-4200H, DDR3-1600, Win 10 x64 1607.
Software used: SQL Server 2016 SP1, VS 2017, .NET 4.6.1, EF 6.1.3, LINQ to DB 1.8.3, EF Core 2.0.
Northwind database will be used.
You can see SQL-queries and testing methods in one of previous article.
Simple TOP 10 query
Further the gray part of bar denotes the context initialization.
EF Core still has a big overhead comparing to ADO.NET and LINQ2DB on simple queries. In my opinion performance impact can be from 50-70% for simple systems to 5-10% for enterprise systems (this is for simple queries).
Also you can see EF Core can't execute raw SQL queries fast. And EF Core can't execute custom result - you limited to entities.
Compiled EF Core queries are a bit faster (but still far from ADO.NET or LINQ2DB).
Simple TOP 500 query
EF Core queries (both LINQ and raw SQL) performance is near Entity Framework 6. ADO.NET and LINQ2DB are a little faster.
EF Core raw SQL queries are dramatically slow, so you won't see them later.
Complex TOP 10 query
For complex queries EF Core looks pretty well and can be compared to ADO.NET and LINQ2DB. Note that ADO.NET and LINQ2DB raw queries are a bit faster.
Complex TOP 500 query
Complex queries with many rows - both LINQ and compiled EF Core queries performance is as ADO.NET and LINQ2DB.
EF Core 2.0 still can't be used for raw SQL queries nor for speed nor for impossibility of executing custom data result.
A bad thing also is that EF Core is slower for simple queries.
The one good thing about EF Core is that it is nearly as fast for complex queries as ADO.NET and LINQ2DB (but anyway a bit slower).