Whitey - 6:06 am on Mar 13, 2011 (gmt 0)
Server speed is a factor that helps for a better crawl, potentially more frequent per page, as well as deeper into the site. But it's not a factor for staying in the index.
The number of pages that actually stay in the index, rather than just get spidered, is related very strongly overall to the backlink strength of both the home page and how that link juice is distributed internally. Backlinks to deeper pages are also a big help. Many webmasters have noticed that there seems to be a formula (admittedly a moving target of a formula) for how many pages will be retained in the main index for any site. It's not a simplistic formula, however. It's not a flat percentage, nor is it a certain hard number.
Page load speed is still not an active factor in ranking (or crawling or indexing) but it is definitely on the horizon as a ranking factor, possibly this year. The early notices and the push from Google to inform webmasters and give them somne tools and education began last year.
I'm following up from an 2010 earlier thread where it was speculated that Google would commence the use of this factor in it's algo. Has anyone noticed if site speed is now a ranking factor?