There are many factors that will have an effect on your SEO. Having clean, fast loading pages with well optimized images will give you a better chance of getting ranked higher in the search engines. When it becomes more difficult for spiders (robots) to index your pages they tend to spend less time on your site, thus indexing fewer pages
Keeping your code lean and clean makes it much easier for search engines to index and it also will help keep potential clients and customers on your site. If pages take a long time to load, a potential customer may just click away from your site never to return. Remember, first impressions are lasting impressions.
Too manywebsite enhancing scripts can have an adverse effect on SEO. Sometimes it is better to have less “pretty” and more efficient and to the point code. Lets face it, the main reason a business has a website is to get their point across. When a client or customer is searching for an answer to a particular question whether it be information on a product or an informative article you have written, they want to be able to locate it quickly.
Make sure the code is necessary for your site. Ask yourself this question. Will it help sell my product or service? If the answer is yes, then use it. If the answer is no, take a close look at what the code does for your site and decide whether or not it is worth the lag in load time.