Quality compression vs. dimension resizing at the edge: a Nairobi store wins both ways

Quality compression vs. dimension resizing at the edge: a Nairobi store wins both ways
A marketplace served one 2400px master image to every device. On desktop it looked fine; on a Nairobi phone, the browser downloaded the full 2400px file and shrank it in software — 480KB to paint a 360px thumbnail.
Mobile data pages averaged 3.1MB and bounce on slow connections ran high.
The team's first instinct was to crank edge quality compression lower. That helped bytes but softened the desktop hero badly.
The real fix split the levers: edge dimension resizing keyed on device width served a 360px file to phones, while quality stayed high. Compression handled the final byte trim per size.
Mobile image payload dropped from 480KB to 34KB per thumbnail. Page weight on phones fell to 700KB.
The number that mattered: thumbnail bytes from 480KB to 34KB.