Cookies in Safari

I recommend that you avoid using Sophos, as it could actually increase your Mac's vulnerability, as described here and here.

Macs are not immune to malware, but no true viruses exist in the wild that can run on Mac OS X, and there never have been any since it was released over 10 years ago. The only malware in the wild that can affect Mac OS X is a handful of trojans, which can be easily avoided by practicing safe computing (see below). Also, Mac OS X Snow Leopard and Lion have anti-malware protection built in, further reducing the need for 3rd party antivirus apps.

Mac Virus/Malware FAQ​

1. Make sure your built-in Mac firewall is enabled in System Preferences > Security > Firewall
   
   
2. Uncheck "Open "safe" files after downloading" in Safari > Preferences > General
   
   
3. Disable Java in your browser (Safari, Chrome, Firefox). This will protect you from malware that exploits Java in your browser, including the recent Flashback trojan. Leave Java disabled until you visit a trusted site that requires it, then re-enable only for the duration of your visit to that site. (This is not to be confused with JavaScript, which you should leave enabled.)
   
   
4. Change your DNS servers to OpenDNS servers by reading this.
   
   
5. Be careful to only install software from trusted, reputable sites. Never install pirated software. If you're not sure about an app, ask in this forum before installing.
   
   
6. Never let someone else have access to install anything on your Mac.
   
   
7. Don't open files that you receive from unknown or untrusted sources.
   
   
8. For added security, make sure all network, email, financial and other important passwords are long and complex, including upper and lower case letters, numbers and special characters.
   
   
9. Always keep your Mac and application software updated. Use Software Update for your Mac software. For other software, it's safer to get updates from the developer's site or from the menu item "Check for updates", rather than installing from any notification window that pops up while you're surfing the web.

That's all you need to do to keep your Mac completely free of any Mac OS X malware that has ever been released into the wild. You don't need any 3rd party software to keep your Mac secure.

Cookies are normal and have nothing to do with how fast a site runs. If you're on YouTube, Flash may be the culprit. For Flash-related issues:

• Find your Flash version and make sure it's the latest version available. Never install or update Flash from a pop-up on a website. Always go to Adobe's site to get Flash or updates.
• Install ClickToFlash (Safari), Flashblock (Firefox) or FlashBlock (Chrome) to control which Flash content plays on websites.
• Try using the YouTube HTML5 Video Player to watch YouTube videos, when available. (May impact fullscreen viewing. See link for details.) As far as performance impact, YMMV.

 

Don't delete the cookies, eat them!