I'm Andres Clari from SteelCode Consulting, and I have ample experience building complex RubyOnRails sites.
I've built them from scratch, using APIs, cloud storage on Amazon S3, integrated backups, etc. And I've done some work in performance enhancing on databases and website load, basically by performing bulk transactions instead of 1 by 1 inserts and selects, and prefetching and caching, any dataset can be handled.
I've also built the frontend for these sites using jQuery, Bootstrap, and recently I built a whole site which Rails only provided the backend and all the frontend was done in EmberJS.
So I feel I can help you with anything you might need for this project.
I would love to hear more of your project, and what kind of tasks we would be implementing.
Let me know if you want to work together on this.
Regards, Andres.