Today’s visitors prefer fast loading websites. Their chance of leaving the page is directly proportional to loading time. Most of the visitors want the website to load below 5 seconds. Visitors spend less time in slow websites. Slow loading websites which are not optimized properly have adverse effect on search engines. Optimized websites can minimize CPU and bandwidth usage. Google has also included site speed as one of the metrics of search ranking algorithm.
Here are some free online tools for developers/site owners to check their website performance.