Performance differences between visibility:hidden and display:none

display:none; elements are not in the render tree all, so they will perform better at face value.

I doubt you will have any real visible performance problems from this though. If you need opacity: 0 or visibility: hidden because of their functionality, then just use them. If you don't need the functionality, then use display: none;

If you are toggling between visible and invisible states via javascript then visibility:hidden should be the better performer. Seeing as it always takes up the same amount of space in both visible and hidden states it won't cause a reflow of the elements below it every time you make it appear of disappear. For display:none you are removing it from the flow of the document and then when you set it to display:block you are rerendering it and pushing everything below that element down, essentially laying all that stuff out again.

But if you are doing something like toggling visible states on button presses then you really should be using what suits your needs rather than what performs better, as the performance differences are negligible in such cases. When you are animating with the dom at around 20 times per second THEN you can worry about the performance of visibility:hidden vs display:none.

visibility: hidden does not cause a re-flow on the document, while display: none does.

display: none: The HTML engine will completely ignore the element and its children. The engine will not ignore elements marked with visibility: hidden, it will do all the calculations to the element and its children, the exception is that the element will not be rendered to the viewport.

If the values for position and dimensions properties are needed then visibility: hidden have to be used and you have to handle the white space in the viewport, usually by wrapping that element inside another one with 0 width and height and 'overflow: hidden'.

display:none will remove the element from the document's normal flow and set the values for position/height/width to 0 on the element and its children. When the elements display property is changed to other value than none, it triggers a complete document re-flow, which can be a problem for big documents - and sometimes not-so-big documents being rendered on hardware with limited capabilities.

display: none is the natural and logical solution to use when hiding elements on the viewport, visibility: hidden should be used as a fallback, where/when needed.

EDIT: As pointed by @Juan, display: none is the choice to go when what you need is to add many elements to the DOM tree. visibility: hidden will trigger a re-flow for each element added to the tree, while display: none will not.