High-Level Guide to Scaling Meteor

The first and highest-impact place to optimize is in softwareland:

• Mongo schema design, indexing, and oplog
• Subscription and query design (also try to avoid types of queries that use the polling driver)

For server architecture, place at the front a SockJS-safe, sticky-session load balancer that distributes connections to app servers based on least connections.

On the application servers:

• CPU: Run an instance of meteor for each CPU core, since node is single-threaded.
• Memory: Meteor’s MergeBox is keeping on the server a copy of each client’s client-specific subscription data, so make as many publications as you can general-purpose (as in, they return the same data for all users or a group of users, rather than different data for each user).

A floor for your per-client memory usage is how much additional memory your publications take up when another user connects. Looking at...