Optimize usage of java streams

A big chunk of the temporary garbage churn in the application running in Sloth (low tops, high event, low latency) is spent on wrapping collections in streams. It is done in a few hotspots, so if we ever need to optimize garbage creation, this might be an easy win. Below is a flame chart of allocation places

Start with the linked flame chart and identify the allocation hotspots where collections are wrapped in Java streams. Trace those hotspots through the application and compare allocation and latency behavior after reducing stream-related garbage creation.

Written by the indexing model from the issue text.