As soon as you publish your site you should make sure that your site is as fast as possible. Slow sites may not necessarily make your SEO rankings drop, however, if a visitor tries to access your site and it takes more then a few seconds to load the site, he might leave the site before it loads. This is registered as a bounce by Google, and will raise the bounce rate. A general rule of thumb is to keep the time needed to load your site under 2 seconds. There are a few sites that can measure the speed for you:
- PageSpeed Insights from Google
- Y-slow (as a browser extension)
- Pingdom Tools
- GT-metrix (combines Pagespeed Insights and Y-slow in one go)
Usually you will receive some input about what's good and what isn't. You should be aiming at a Score close to 100, and a load-time of less then 2 seconds:
What is also good about these tools is that all provide a lot of details of why a site runs slow, or general advice about this. Fortunately, for most issues there is a solution, either within the Joomla core (like caching or Gzip), or using an extension.