In the case of something simple, like an ID, tag name, or class name, Sizzle (the jQuery selector engine) simply uses the native JavaScript equivalent (e.g., getElementById(), getElementsByTagName(), getElementsByClassName()). So, if you grabbed your table elements using one of those functions, you're not going to be incurring any significant penalties by using the jQuery version.
Regardless, speed isn't the most important thing to consider. Modern browsers (let alone computers) are fast. A linear search in place of a logarithmic search isn't going to noticeably negatively affect you. In the real world, in the vast majority of cases, code readability, reusability, and overall elegance is far, far more important than pure speed.
Regardless, speed isn't the most important thing to consider. Modern browsers (let alone computers) are fast. A linear search in place of a logarithmic search isn't going to noticeably negatively affect you. In the real world, in the vast majority of cases, code readability, reusability, and overall elegance is far, far more important than pure speed.