safari 3.1 setAttribute very very slow!!

Hi I'm developing an application using SVG and CSS and, after upgrading to 3.1, I discovered that the rendering of an SVG component after changing its class attribute is absolutely slow: it takes forever (literally).
It is a simple element.setAttribute('class', classname).
This only takes effect AFTER I reload the page, which obviously, is not what I want.

Is there a simple solution to this? does anyone else have the same problem?

As a last solution I would like to downgrade to the previous 3.0.4 version. Can anybody point me to a working http address where I can download an old version of Safari?

Thanks,

pomense