Two small jobs worth doing properly

Two tasks that nobody enjoys and that repay attention out of all proportion to how long they take. Neither is interesting. Both are among the highest-return twenty minutes available on a typical site.

Images: the most common cause of a slow site

Page speed advice tends toward the technical — caching layers, script loading, server response times. All of it matters and none of it matters as much as the fact that most slow pages are slow because somebody uploaded a photograph straight off a camera or phone.

A modern phone produces images several thousand pixels wide and several megabytes in size. Displayed in a column eight hundred pixels wide, the browser downloads the whole thing and then throws most of it away. On a good connection this is invisible. On a phone, on mobile data, it is the entire experience.

The order matters. Compressing hard without resizing is the common mistake: it degrades visible quality while leaving the fundamental problem, which is that the file describes far more pixels than anyone will see.

The fourth row in the table is worth its own mention because it fixes a different problem. Without stated dimensions, the browser does not know how much room to leave, so the page reflows as each image arrives — which is the effect where you go to tap something and it moves. It is measured as a ranking signal, and more to the point it is genuinely irritating.

Data: what a spreadsheet does to an export

The second job is converting structured data — an export from one system into a format another system can import. The usual approach is to open it in a spreadsheet, tidy it, and save it out again. That step is where the damage happens, silently.

• Leading zeros disappear. Postcodes, product codes and phone numbers become numbers, and the zeros are gone before you notice.
• Dates get reinterpreted according to local convention, so the same file means different things depending on who opened it.
• Long identifiers become scientific notation, which is not a display quirk — it destroys the value.
• Anything resembling a formula gets evaluated. A field starting with an equals sign is a genuine security consideration as well as a data one.

None of these produce an error. The file saves cleanly, imports cleanly, and the problems surface weeks later as records that do not match, orders that cannot be found, and a customer whose phone number has one digit fewer than it should.

The fix is to convert directly between formats without a spreadsheet in the middle. Where a spreadsheet is genuinely needed, import the file rather than opening it, and set every column that is not arithmetic to text before the data is parsed.

Why these two together

They share a shape. Both are small, both are boring, both are usually delegated to whoever has a spare moment, and both fail silently in ways that are much more expensive to discover later than to prevent now. A site that is slow on mobile and a database with corrupted identifiers are each the accumulated result of a hundred small decisions nobody thought worth attention.