Performance and usability also goes beyond providing a better user experience. As of April 2015, Google are now ranking website performance and having a responsive website as key parameters as to where your site is ranked on their search engine.
These could literally be the difference between being on the first page or the second. Being the 10th result (i.e. still on page one) compared to the 11th (top of page two) equates to double the amount of click through traffic.
The first page of Google equates to 94% of clicks, the second page equates to 6%.Keywords are still important, but they're no longer the only parameter that matters.
It's surprising how many sites I come across that have no optimisation setup at all. Investing a bit of time to reduce image sizes, condense and compress files and organise the site structure to load faster, can go a really long way, and not just on the SEO front.
Typically, when a user lands on a website, you have between 10 and 20 seconds to engage them before they leave. When you consider this time also includes loading times, it becomes even more crucial to have your site served as quickly as possible. If your site takes 10 seconds to load, you could be losing customers straight off the bat! Through various different techniques and custom scripts, i've developed a way to ensure that your site will load quickly and efficiently, giving you as large a window of opportunity as possible.
The last part of the puzzle is to use analytics to measure everything that your site is doing, from number of visitors, to what pages they're viewing, where they've visiting from and what devices they're using to view the site. Using these analytics, you can then figure out what you're doing well and where you're not quite as successful, you can improve upon those areas. It's undoubtedly the best way to measure success.