We have just upgraded to 0.12.0. As we are using c.use :rails this would enable allocation tracing for our deployment. Shortly after deploying to production we have observed a large increase in the memory footprint of our processes. Some samples from our monitoring:

I have not found an option in the use :rails configuration to disable instantiation tracing, so it's hard to say if this feature is where the issue comes from. We have since reverted the gem upgrade to return to our usual memory consumption.