In some ways, performance considerations for 3D games in browsers are pretty similar to those for consoles and desktop games. The biggest difference is that all resources must (at least initially) be streamed to the client instead of read from a disk. For complex 3D games with gigabytes of assets, overcoming this limitation for low-bandwidth clients can be a serious challenge.
As legendary programmer Donald Knuth wrote:
"Premature optimization is the root of all evil."
This section discusses best practices and suggestions to get great performance out of your game, but before expending significant effort, you should measure and test your application to see where the bottlenecks are and whether the effort is worthwhile.