It should be noted that Meteor is simply Javascript and Node.js. Yes, it's a very specific implementation of those two technologies, and has it's own unique ecosystem, and leverages isomorphic APIs and a JSON datastore to achieve some truly amazing results. But, at the end of the day, Meteor is a web technology, and it's written in Javascript. So all of your typical javascript performance techniques still apply. Start there.
25 Javascript Performance Techniques
Performance Optimizations for High Speed Javascript
Optimizing JavaScript Code
Performance Tips for JavaScript in V8
10 Javascript Performance Boosting Tip
Write Efficient JavaScript
Improving the Performance of your Meteor JS projects