同时从远程服务下载JSON数据

I am pulling JSON data from several remote servers concurrently over HTTP, using a WCF service on both the client and server endpoints. I'm noticing that for each successive request that starts asynchronously the length of time that http request takes is generally increasing, even if the amount of data is not necessarily increasing. In other words if I start 12 thread pool threads (using Func<>.BeginInvoke) then each request, after being timed, is showing up in my logs as such:I am pulling JSON data from several remote serv