Making sure you have the right site architecture is an important search engine ranking factor. Having the wrong architecture / web design layout can hinder or negate your efforts.
Site Crawability
Search engines “crawl” your website by jumping from one page to another, following the links on your pages.
The crawler makes a copy of each page and stores it in the search engine’s index. When someone searches for a phrase, the search engine looks through its index and returns the most relevant results. The best results, as determined by the search engine, are returned first.
To be found, you have to be in the index. For a given page to be indexed, the crawler has to be able to find the page from links to it on other pages. Normally this is not a problem as most sites have a menu structure arranged like a tree. Main topics are at the top and include links to sub pages covering related topics. The search engine can use the links in your menus to find all the pages on your site.
There are some practices that can hinder the search engine’s crawler from finding all the pages on your web site. For example, JavaScript or Flash can potentially hide links.
Those Flash based restaurant web sites are an example of bad web site architecture.
A good idea is to submit a site map to each search engine. Both HTML and XML sitemaps help the search engine index your web site efficiently.
Good site architecture should help both the end user and the search engine find the content on your web site.
Site Speed
Google has stated that the speed of your web site is a factor in the ranking process. Faster is better.
Increasing the performance of your web site by making sure your web site isn’t hosted on oversold web servers from low cost web hosting companies might be a good idea.
Although site speed might be a minor factor in determining your page rank, having a faster web site will help your visitors. No one wants to wait for a page to load. Your visitors might just leave before your content loads leading to a low time on page metric. A metric we know Google is tracking and using.
Are Your URLs Descriptive?
Having your key words in the URL for your page can help your ranking. It’s a minor search engine optimization factor.
The real reason to have descriptive URLs is that research shows the pages with short, descriptive URLs are clicked on more frequently then other pages. Again we know that Google is counting clicks, so descriptive URLs are a good idea.