```ruby
if ENV["RACK_MINI_PROFILER"].to_i > 0
  require "rack-mini-profiler"

  Rack::MiniProfilerRails.initialize!(Rails.application)
end
```

Make sure rack profiler on in dev environment
user
```ruby
if Rails.env == 'development'
  require "rack-mini-profiler"

  Rack::MiniProfilerRails.initialize!(Rails.application)
end
```
assistant