Firefox to US$7,500 cash reward) to researchers who discover severe security holes in Firefox. Official guidelines for handling security vulnerabilities discourage early disclosure of vulnerabilities so as not to give potential attackers an advantage in creating exploits. Because Firefox generally has fewer publicly known security vulnerabilities than Internet Explorer (see "Comparison of web browsers"), improved security is often cited as a reason to switch from Internet Explorer to Firefox. "The Washington Post" reported that exploit code for known critical security vulnerabilities in Internet Explorer was available for 284 days in 2006. In comparison, exploit code for known, critical security vulnerabilities in
Firefox and sixth-fastest browsers, respectively, on startup, 3.5 was third- and 3.6 was sixth-fastest to load nine tabs at once, 3.5 was sixth- and 3.6 was fifth-fastest on the JavaScript tests. They also concluded that Firefox 3.6 was the most efficient with memory usage followed by Firefox 3.5. In February 2012, "Tom's Hardware" performance tested Chrome 17, Firefox 10, Internet Explorer 9, Opera 11.61, and Safari 5.1.2 on Windows 7. "Tom's Hardware" summarized their tests into four categories: Performance, Efficiency, Reliability, and Conformance. In the performance category they tested HTML5, Java, JavaScript, DOM, CSS 3, Flash, Silverlight, and WebGL (WebGL 2