IT contractors doing web development work will be majorly affected by Google's decision to factor site-speed into search engine ranking, a business consultancy claims.

Developers must now ensure that the site they are developing is fast enough, accounting for potential spikes in traffic and the number of different graphics that may be in use at any one time, according to Idea Taxi.

Google claims that it is only a slight amendment to its current search functionality, with tests prior to the announcement showing that fewer than one per cent of searches were affected by the change.

However, the director of Idea Taxi, Sam Tilston, believes Google is playing down the impact of the change.

"This is a huge move and has major implications in terms of design and coding. Site owners must look at a range of factors now [so] as to not endure the wrath of a Google penalty resulting from a slow site," he said.