In my experience, the slowness have come from two main areas: Naïve Active Record objects - that is, hydrating rather than explicitly plucking. AR is horribly

In my experience, the slowness have come from two main areas: Naïve Active Record objects - that is, hydrating rather than explicitly plucking. AR is horribly slow when it constructs db objects. Streaming and recreating hash objects over and over and over again in for-loops. For a primary construct, it’s surprisingly slow to work with.