WWW in Webplayer lag problem

I am downloading a bunch of icons from a server using the following code in a coroutine.

WWW www = new WWW(thumbnail);
while (!www.isDone)
	yield return 0;

I first started all the tumbnails at once, which worked great in the editor. But when I tested it on the web player, it takes over 5 seconds to start to download the 20 icons. This completely freezes for 5 seconds. The problem is the WWW www = new WWW(thumbnail); line. Why is WWW causing lag in the web player, and is there a way to work around it?

In the web player build the WWW is implemented using the browser, which, after all, knows a thing or two about fetching data from servers. So, your script code is asking the browser to make these requests. Possibly your browser is configured to not allow multiple, parallel downloads, or your server is throttling the delivery to you. (Inside the editor curl is used.)