Internet Explorer 9 is bar far the safest and most secure browser right now. It is also the slowest of the major browsers.
By far the slowest in some areas, faster in others. But, today, all browsers are fast enough. I honestly notice no speed differences between IE and other browsers, though I'm sure if I ran benchmark tools, a difference would show. But, every page I go to renders in just about a blink of an eye. Menu clicks, opening new tabs, the same. I never wait for my browser.
Personally, I run IE9 the vast majority of times, though I do have Firefox installed. Protected mode, Tracking protection and the newer download manager bring a lot of benefit. IE still has no built in spell check, but iespell works great in IE 9.