Shipping less.
WHAT TO MEASURE FIRST
Total output size, and what the largest contributors are.
HOW
Bundle analysis tooling.
WHAT TO DO ABOUT LARGE DEPENDENCIES
Establish whether you use enough of them to justify their size Import only what you need, where the library supports it Find a smaller alternative Remove it
WHAT TREE SHAKING DOES
Removes code that is never used.
WHAT PREVENTS IT WORKING
Libraries not published as modules Imports of an entire library rather than specific parts Side effects preventing safe removal
WHAT CODE SPLITTING PROVIDES
Only loading what a route needs.
WHAT TO SPLIT
By route, always Large components used rarely Heavy dependencies used in one place
WHAT TO DEFER
Anything not required for the initial view.
WHAT TO SET FOR ASSETS
Long cache durations, with versioned filenames.
WHAT TO ENABLE
Compression, on the server.
WHAT TO CHECK AFTER EVERY CHANGE
Whether the bundle grew.
WHAT TO AUTOMATE
A size limit, failing the build when exceeded.
