I would suggest run the test up to about 300 objects, then click "pause" and "graph it".
dhtml benchmark 01 | dhtml benchmark 02 | graph merger
The tests were made with an AMD Athlon II X4 3.2GHz, 4GB RAM, integrated ATI Radeon 3300 graphics, running under Windows 7 Professional 64 Bit.
Out of competition, old browser
Stopped at 30fps
Each browser was stopped at 300 objects.
While Internet Explorer 9 and Firefox 5.0 perform better with a few elements, the variance of Opera's over all performance is smaller and such it offers higher frame rates with more than 100 rendered objects. Firefox and Chrome show a very jittery behavior, it seems that they prefers certain numbers of elements or have some cache problems. Firefox breaks down like Internet Explorer, whereas Chrome's performance is between Opera 11.11 and 11.50. Interestingly Internet Explorer 9 32 bit performed better than Internet Explorer 9 64 bit.
Opera can render more than 995(!), Chrome more than 780 elements and Opera 11.11 still more than 740 elements at the same time before they break down to the same 33 fps rate like Internet Explorer 9 or Mozilla Firefox 5 with 300 rendered elements.
Thanks To Remco for providing the tests.
newer test results | dhtml benchmark 01 | dhtml benchmark 02 | graph merger