What problem are you trying to solve?

Focus on the what and why of the need you have, not the how you'd like it solved.

Improved performance for lookups from large to small collections (where many origin documents match the same looked-up document(s))

What would you like to see happen?

Describe the desired outcome or enhancement.

Batching or cache (within a single aggregation execution), with support for sharding and transactions.

This is represented in some longstanding backlog tickets: SERVER-21284, SERVER-21312

Why is this important to you or your team?

Explain how the request adds value or solves a business need.

What steps, if any, are you taking today to manage this problem?

Slow lookups can be resolved via data-modelling (eg. nesting and duplicating) but this is sometimes not possible.