It aggrevates me when a site that I try to open because of its textual content takes 30 seconds to render since there's too much Javascript going on. Then I'm typically sitting there thinking: "how hard can it be to display a piece of text?" Because of this, when I see my CPU spike as I try to open a website in a new tab, I very often decide to simply close the tab again and do without the information I originally came there to see. This happens a lot for me with online magazines, such as wired or techcrunch. One trick is to invoke the "Readability" bookmarklet if I can get to it fast enough, i.e., before the JavaScript has frozen my browser completely.
Of course I understand that I am part of a tiny minority. And probably I'm not part of your target group anyway. And the web is so much more in 2013 than pages with text on them.
If you do, however, want someone like me to come to your site, you better remember to keep it dinosaur-friendly.