Discussion: GraphQL performance issues

so, i've been digging a little bit and stumbled over the SchemaBuilder, which makes up quite a significant portion of GraphQL requests (Blackfire example: http://img.mia3.com//?i=BChcGpHy1ouvUeKc.png)

Imho, this should be cached/cachable, right? I already tried some approaches and realized, that it's not that easy because of the Closures used for [resolveType](https://github.com/api-platform/core/blob/master/src/GraphQl/Type/SchemaBuilder.php#L122) and [fields](https://github.com/api-platform/core/blob/master/src/GraphQl/Type/SchemaBuilder.php#L412).

The resolveType could be replaced by a static function instead of a closure, but the fields is a bit trickier. I tried to replace the closure with the direct result of the internal getResourceObjectTypeFields method call, sadly, this turns into a recursive loop, because the related objectTypes are not registered yet at this point.

I have 2 Ideas how this whole thing could be approached:

1. somehow fix the recursive issue, maybe by registering the objectType first and "override" the fields after the object itself was resolved
2. Rewrite most of the SchemaBuilder to generate a "cached" Schema.php file that contains everything and is simply included on load.

Is there another way i'm maybe not seeing?

Cheers
Marc