Flash banner ads and page speed / size

I've been trawling the net and can't find a definitive answer to this question so thought I'd post here to see if anyone knew. I'm trying to assess the impact of banners on my page speed and up until recently this has been easy to do. We specify a limit on SWF file size for banners of each dimension (468X60 etc) and there's no problem with this.

However, recently advertisers have become more and more fond of sending through code references rather than the banner ads (SWFs) themselves. So, for example I get a code block that I put online and it show's the banner ad and that seems fine.

Question is though, how can I assess the impact these banners have on my site in terms of slowing the load speed or causing HTTP requests. Maybe this question is best served by an example:

Advertiser A supplies me with code for a banner ad. By copying and pasting this code into a blank HTML file I can see the banner and check that it seems ok, it's served off Advertiser A's servers so should be fine. However, when I put this banner live on my site I don't know if the size of it impacts my page load speed or the rendering speed of my page.

Also, if the banner is one of those banners that has flash video in it, the eventual file size can be over 1 meg, which I presume *must* load gradually via streaming rather than loading all at once. So, to summarise I'd really like to know the following:

1) Do banners that aren't hosted on my site affect the load speed / rendering speed of my site?

2) How do large, streaming video banners affect page load speed? Do they load a static image and only begin to stream once mouse-overed?

3) If externally referenced banners do not impact my page speed, should I drop my file-size limitations entirely where external banners are concerned?

Any help anyone can provide with these questions is much appreciated.

Thanks!

Hi,

1. as far as i know banner ads that aren't hosted on your site will still affect the loading speed and rendering of the site. If you look at your resource monitor you will notice a small increase in the processing of the ram and the graphics card when viewing. However banner ads are generally pretty small and shouldn't take up massive amounts of processing power.

2. Not all streaming video banner ads run when a mouse is placed over them. Some play video clips in thier natural state but without sound. These will also effect the processing power but the quality of ones that play naturally are generally lower than ones that need rollovers.

I would be interested to hear other opinions on this issue as it is interesting to see the effect of these new banner ads that offer increased interactivity and video intergration.