Code review and optimization (nodejs, rethinkdb)

We need code review and looking for ways to optimize a small stats service and db . It's all nodejs and rethinkdb. It's a small app we have grown dependent on a lot and I want to look for any areas to improve and harden the system. we can dynamically insert events to be logged. then we have the ability to send 3 types of queries to it for getting data out of it. Overall the system works great we just want to get ahead of any things. I would like you to estimate maybe 4 hours of time to review the system and document a number of recommendations and some estimates for implementing those recommendations. we will review and if we decide to move forward we will hire you for specific next tasks. System uses nodejs, flatiron, rethink db We are looking for things like -Add gzip as option -Decrease response time, right now its around 300ms which is fast but 100ms is faster -Ideas around caching for exact same requests in a short period of time -Do you see any scale issues as we go from 1000's of rows to 1million? -Are there any other approaches we should be looking at like bitmap index, or other advanced techniques for massively scaled quick queries for time series data like this.