Improve performance when loading large amount of uncached content

Description

Profiled and optimized the API used when the cache is missed and data is loaded from the database. This is a common scenario when starting a web site with a cold cache. Performance improvements up to 50% for cache misses in some scenarios. The results vary depending on the size of content types and data being loaded.

Breaking changes

• CreateWritableClone is used to create new instances of content instances when loading from database