What to aim for.
A REASONABLE TARGET
Content visible within about two seconds on a decent connection.
Page weight under a megabyte where possible.
WHAT IS UNREALISTIC
A perfect score on every test Instant loading of an image-heavy page Matching a site with a fraction of your functionality
WHERE THE GAINS ARE
The first improvements are large and cheap: images and caching.
The last improvements are small and expensive.
Stop when the effort exceeds the benefit.
WHAT TO PRIORITISE
The pages visitors actually load Mobile performance The checkout or enquiry path
THAT LAST ONE
A slow homepage costs you some visitors. A slow checkout costs you sales.
HOW TO TRACK PROGRESS
Measure before, make one change, measure after.
Changing five things at once tells you nothing about which helped.
WHEN TO STOP
When the site is fast enough on a phone on mobile data.