Grauw’s web spot - The www-style CSS FAQ

Grauw’s web spot - The www-style CSS FAQ

Q: What is incremental rendering
Incremental rendering is the ability to display the contents of a document which is still being loaded. This is a valueable asset, because users do not have to wait for the entire document to load, which can take a fair amount of time depending on the size of the document, the bandwidth of the client, the bandwidth of the server, the locations of the client and the server, etc.

An important part of incremental rendering is to avoid reflows. A reflow of the entire document means it has to be drawn all over again, which is a very slow process, and thus has to be avoided whenever possible.

Thus, incremental rendering and avoiding reflows is important to CSS because it keeps things fast and simple. Especially on lower-end systems such as mobile phones, webtv, and browsers on old computers such as the MSX reflows are extremely costly operations. But also on modern systems such as desktop PCs they have a considerable performance impact, resulting in very slow responsiveness while loading, and often also ugly visible ‘snaps’ when the location of things change as more content is loaded (you can often see this in table-based layouts).