Absolute Positioning Performance

Excessive use of absolute positioning is a design problem, but it's not so much because of any a performance issues - I don't know of anything performance-wise which would make me hesitate to use absolute positioning when I needed it.

The real problem with absolute positioning everything is that you tend to tie your layout to fixed sizes, which can make things go completely nuts if you have to adjust for things which change size.

For example, what happens if you want to increase the font size of your site? If everything is absolutely positioned, you'll have a huge effort to re-align everything.

In the same vein, absolute positioning almost always means the entire layout is positioned and sized in pixels rather than em units or percent. Again, nothing wrong with using pixel sizing, but it does generate accessibility issues when people try to adjust the site themselves (eg with zoom or a magnifier, or just changing the font sizes, etc)

And have you tried viewing your site on various mobile devices? Sites that are rigidly designed are generally the worst when it comes to viewing on a smaller screen size. Far better to have a fluid design that just works wherever you use it, rather than having to have an entirely separate site for mobiles.

To me, using absolute positioning in relatively-positioned elements (like, within a footer) is time-saving. Using it everywhere could be messy when you have to change a layout (columns, headers...).