Reflection is killer for performance because it brings Java/Go down to the level of a JIT-less language like Python (and ORMs aren't too kind to JITs in e.g. Ruby/JS either). The problem with reflection in Go/Java is mostly that it's hard to read, since the reflection-ful APIs are hosted rather than native syntax.
Agree reflection has (often big) trade offs but its not as bad as it was years ago, especially if its used during construct time rather than runtime, if you combine it with runtime caches you still get the benefits imo
