Everyone knows that users hate slow load times for websites, but were you aware that search engines also keep track of page loading speed?
Google won’t say how heavily it weighs this as a factor, but it has been confirmed that page speed for both desktop and mobile have an effect on search result rankings. Google’s page speed tool actually provides feedback on speed of mobile sites now, so it is time that anyone building a website takes the development of a fast mobile experience into consideration.
A few years ago, mobile specific websites were the way to go (essentially a second, mobile friendly version of the same website). They are still a usable option, but as responsive web design becomes the predominant trend, major search engines favor responsive websites over mobile-only websites.
It is pretty easy to determine why – the end user is viewing the same exact website, so the content is sure to be the same as it is on a desktop. This creates an experience where there is no duplicate content, and it is much more comfortable for the viewers to not have to switch over to another form of media and see a change of content.
Overall, using a secondary mobile website can be done in a way that won’t cause any harm to your search engine optimization, but for the sake of enhancing user experience and making your own website maintenance more efficient, following the responsive trend is the way to go.