Modern websites are increasingly more complex, and many are not just plain HTML but a complete web app that could consume large CPU & memory resource on your Mac. We’re all too used to opening many tabs of web sites and web apps, and do not realise some of these sites are slowing down our Mac.
If you have one too many Safari tabs opening and your Mac appears to be not as responsive, it pays to troubleshoot Safari’s memory usage.
For each tab that you open, Safari spawn a “Safari Web Content” process. Go to Activity Monitor, click on the CPU tab and then click to sort by Process Name and look for “Safari Web Content”.
Check to see if any process is having high CPU usage constantly. To find out the URL behind each Safari Web Content process, simply mouse over the process name.
Similarly, click on the Memory tab to check if there is any Safari Web Content process with high memory usage.
It might surprised you to find out that many website processes are consuming more memory than native OS X app. Typically each Safari Web Content process is consuming less than 100MB of memory. Pay attention to those Safari processes that display number higher than 100MB.