Basic gems list for profiling Ruby on Rails application

it’s a common situation when one loading model service used in many places, and for different places, you don’t need to preload some relations which is clearly needed in some other places

Well, memory is also limited. I would make a service to accept a parameter with an associations list in the rails native format and pass it through the call.

rails_panel

Years ago when I was writing some Rails, I extended rails_panel as described here; I have no idea if it still works, but you may find it interesting to tweak the code and/or use these extensions as is.