On Tuesday, 18 June 2013 at 07:58:06 UTC, Kenji Hara wrote:

Inlining should remove performance penalty. Nobody holds the immediately
called lambda, so it should be treated as a 'scope delegate'. For that, we
would need to add a section in language spec to support it.

Kenji:

I've been doing some benchmarks recently: Using an "inlined lambda" seems to really kill performance, both with or without "-inline" (tested with both dmd and gdc).

However, using a named function, and then immediately calling it, there is 0 performance penalty (both w/ and w/o -inline).

Is this a bug? Can it be fixed? Should I file and ER?