Microsoft has released an update for .NET Framework 4.5 which you may have noticed flying past if you keep an eye on Windows Update in Windows 8. The update is described here, and it is a big one. For example, in the Network Class Library:
Assume that you run a .NET Framework 4.5-based application that uses asynchronous APIs to read chunked responses. In this situation, the chunked responses may be read synchronously.
The HttpWebRequest class lets callers read an HTTP response either synchronously or asynchronously. However, if the response is a chunked HTTP response, then parts of the response are read by using synchronous I/O (Winsock calls) even when the caller uses the asynchronous code path. In this situation, the calling thread is blocked until data is received on the network.
Given this and other issues, the update is highly recommended. Maybe we will see fewer pauses in Windows App Store apps, some of which have not delivered on the “fast and fluid” promise.