I have problems with our adserver tags loading much slower than our pages. I often use a CSS hack to that the adserver code loads at the bottom of the page but

I have problems with our adserver tags loading much slower than our pages. I often use a CSS hack to that the adserver code loads at the bottom of the page but is position in CSS at the top. However this can't be applied in 100% of situations...... Has anyone managed to load adserver code with this method successfully? I'll be trying myself this weekend and will report back....!