@operahandsdown: FWIW, just as a test, I went to the https://newegg.rebateaccess.com/ site you noted using Opera 12.14. With JavaScript enabled, the site timed out with only a white screen displayed, though it stalled at 10/11 elements loaded. With JavaScript disabled, the site loaded at 6/6 elements and the "Enter promotion number..." box appeared (though I didn't try to see if that functioned). Apparently, there are multiple elements being called from the site's JavaScript, and the Presto Opera versions don't like either the JS coding or at least one element/reference being called by it...
In any case, like @rseiler, I don't experience the Opera paralysis you described while waiting for the page-load to time out.