to yesteryear's standards such as nHibernate, good old custom ORM, or something like LLBGenPro?

Also, having run the benchmarks, what are your suggestions?

+8  A: 

Rico Mariani is the performance guy at MSFT and he has a nice series on LINQ to SQL performance:

Haven't seen anything with perf comparison to the libraries you mention, but this should give you an idea of baseline perf..

Jeff Atwood
+1  A: 

We had a horrible experience with ADO.NET Entities performance using LINQ: the inheritance slows down things immensely. A small database (say, 100 records or so) with 20 classes of which most were inherited, a query could easily take 10s.

So make the inheritance tree as shallow as possibly when using ADO.NET Entities + LINQ.

Rutger Nijlunsing
+5  A: 

Here is exactly what you are looking for, see ORM benchmarks on

Alex Kofman
Do you mind putting linq2sql in your tests there ?
Probably not, we are not sure yet, but: 1) it's not full-featured ORM; 2) L2S is obsolete now, i.e. Microsoft don't plan it's further development. Surely one can download our test suite and implement those tests for any ORM/DAL.
Alex Kofman
The problem is that the “bench marks” on ORMBattle are not very “real life” and were created by one ORM vender to show his ORM in good light.
Ian Ringrose
LINQ to SQL benchmark is already there, but it isn't officially published yet. See
Alex Yakunin
"to show his ORM in good light" - that's wrong. See the above link. 2 months have passed, and the leaders on each test differ quite significantly.
Alex Yakunin