Eight Best Practices for Building Scalable Systems

Wille Faler has created an excellent list of best practices for building scalable and high performance systems. Here's a short summary of his points:

Offload the database - Avoid hitting the database, and avoid opening transactions or connections unless you absolutely need to use them.

What a difference a cache makes - For read heavy applications caching is the easiest way offload the database.

Cache as coarse-grained objects as possible - Coarse-grained objects save CPU and time by requiring fewer reads to assemble objects.

Don’t store transient state permanently - Is it really necessary to store your transient data in the database?

Location, Location - put things close to where they are supposed to be delivered.

Constrain concurrent access to limited resource - it's quicker to let a single thread do work and finish rather than flooding finite resources with 200 client threads.

Staged, asynchronous processing - separate a process using asynchronicity into separate steps mediated by queues and executed by a limited number of workers in each step.

Minimize network chatter - Avoid remote communication if you can as it's slower and less reliable than local computation.