Predict consequences of installing LESS, CSS3PIE on a high-load project

I faced situation of global site redesign (not appearance, but code architecture and underlying technologies). Website has about 135 000 visitors everyday. And it's crucial to make right decision now.

I had no experience of using LESS and CSS3PIE on such big projects before. Maybe some of you can predict some trouble which I can run into using technologies mentioned above. I would like to know advantages and drawbacks.

Isn't it better to use old tested and reliable methods like sprites for round corner buttons with shadows and gradients? I look at http://zappos.com.开发者_Python百科 They just degrade gracefully in IE and don't use CSS3PIE.

Nobody answered me, so I try to answer myself. Since there are server-side LESS-compilers for all major platforms (Ruby, .NET, PHP) I decided to use LESS but compile server-side instead of using LESS.js which is not good because it prevents client's browser from caching CSS.

As concerning CSS3PIE I don't see any significant drawbacks of using it, a little more load lies on client using IE but it's not so bad.

The only issue I can foresee now is background and decoration disappearing on popups. I have already encountered this problem and posted a question here but no one ever answered.

I would avoid using CSS3Pie for production sites. In my experience, the higher the number of CSS3Pie-rendered elements on the page, the worse IE8/9 will perform.

Specifically, when I was using IE9 with an IE8 document mode, and with at least 2 elements rendered using CSS3Pie (using border-radius and linear-gradient), I observed a noticeable lag when scrolling the browser window. That is, I would try and scroll down the page, and the scroll bar would take a couple of seconds to "catch up" with the mouse pointer.

As soon as I switched CSS3Pie off, no lag when scrolling was observed. The same applies for IE8 in my experience.