performance-pass.txt
This feels slow: <describe what, and where — first load? a click?>

Don't optimise anything yet. First:
1. Tell me how to measure it, with the specific tool and what number
   I'm looking for.
2. List the likely causes for this kind of slowness, ordered by how
   often they're the real one.
3. Tell me which single measurement would tell us which it is.

Once I report back with numbers, then we fix the biggest one.

Optimising without measuring is how people spend a day shaving 4ms off a function while a 2MB image loads above it.