I have noticed on my MacBook 5,1 with 4 GB of RAM that Safari gets sluggish in full screen mode with twelve tabs open. I also noticed that Safari 5.1, which ships with Mac OS X Lion, spins two processes: Safari (currently using 294 MB RAM and 6.2% of CPU utilization) and Safari Web Content (currently using 1.33 GB RAM and 41% of CPU utilization). If I drop out of full screen mode, the RAM allocation remains the same, but the CPU utilization drops to about 1.4% and 8% respectively. Now, I am back into full screen mode, but I have not yet seen the spike in CPU utilization. I currently have three Safari Extensions installed: AdBlock, Awesome Screenshot, and Click to Flash. I also have the latest version of Adobe Flash installed, but I do not have any active Flash content loaded.
I searched online to see if anyone else is having similar issues. I found a thread started by scryedz on the Apple Support Communities, who began the discussion by writing:
Hi everyone! Safari become very lag when I open a new tab or pages, and when I checked Activity Monitor, the one that made my mac lag is Safari Web Content, it can eats 80-90% of CPU.However, it only happened if I open new tab/pages. I never experienced lag with other browser such as Firefox before. Anyone ever experienced this? Any suggestion or solution will be appreciated. Thanks.
Following the thread, it sounds like others are experiencing Safari’s resource hogging and system sluggishness. Some suggestions to fix the problem include deleting Safari’s cache files manually (~User/Library/Cache/com.Apple.Safari) and uninstalling all Safari Extensions.
Hopefully, Apple will address this problem more assertively with a software update to Safari.