In my experience with SQL, a query like that should return in under a second even if you have 100k or more users. There are some other tricks you can use if yo

In my experience with SQL, a query like that should return in under a second even if you have 100k or more users. There are some other tricks you can use if you're clever/lucky as well. If you're just using integer IDs (which is reasonable if your system isn't distributed) then you could order by userid on you ContactMethod table and still get the same speed as you would with no join.