Performance -- every field wrapped is unnecessarily wrapped in a promise

[Utsav2]

Bug report

Every rule evaluation assumes that the return value from the evaluation function is a promise.

Describe the bug

This implicitly converts every response value into a promise. For large, nested responses, this causes lots of promises to be created and immediately resolved, which slows down the event loop and response times per request significantly. I've noticed over a million promises being invoked and resolved in our production environment.

I believe this is the root cause for most of the other performance issues being flagged in this repository.

Expected behavior

GraphQL Shield should only await functions that actually return promises. A lot of other libraries, like apollo-server, await on promises only if the return value is actually a promise.

[OdedNir]

@Utsav2 I'm also experiencing the same thing.

When using applyMiddleware each default field is unnecessary running the rule applied for the type.
Is there an option to choose if it will run once only for the type?