Recently in one of our projects, we decided to take a deeper look at N+1 queries, as well as general DB Operations performance. We’ve started by installing this awesome gem called bullet . This gem, creates a log file for you, where it lists all the N+1 queries found, unnecessary eager loading queries and missing requires. This is quite useful as a starting point for improving your general web application performance.

We’ve successfully cleaned up most of the logged queries and we’ve moved on with our lives. Because our application relies a lot on indexedDB, we’ve never experienced (at least not until today) a lot of hassle after making bullet part of our development environment.

Today we were puzzled by where the heck the application was losing so much time and taking so long to answer to the client side, even after rails logging Completed 200 OK in 551ms (Views: 170.3ms | ActiveRecord: 37.0ms) By a lot of time, we’re talking about 50 seconds until TTFB .

After a lot of head banging against the wall, we’ve decided to move bullet away from our dev environment and…. boom! Performance back to normal.

Lesson learnt: “If you plan to use bullet, use it while you need it and then put it away. It will bite your ass when you least expect”.