How it works
Page speed includes server response, resource delivery and browser work before and during use. A compressed download can still take time to parse or execute. Conversely, a sharp appropriately sized image can be efficient when it is delivered and prioritised correctly.
A realistic example
A glossary page need not download the complete route map for every town just to switch between four versions of one term. Supplying the current term’s equivalents reduces work without changing its appearance. Such removal differs from degrading an illustration or deleting a useful interaction.
What to check
Record the test device, network conditions and cache state. Inspect slow responses, the largest visible content and lengthy browser tasks. Compare the same URL before and after a change, then test navigation, forms and visual stability as well as the score.
Limits and next steps
Do not promise a universal 100 from one laboratory run. Measurements vary and field data represents other conditions. Prefer removing redundant work, reserving layout space and appropriate caching before reducing visual quality or useful content.