TL;DR Using Enumerable.Concat to build a long sequence one item at a time is a particularly bad idea, since enumerating the items will consume a lot of stack space.

A while ago, a customer reported that our .NET application running in IIS started crashing on user registration after …

When you build a GUI, all lengthy operations that can be triggered by the user should take place on a background thread so that the GUI doesn’t become unresponsive. Why would it? Well, it’s because all GUI operations take place on a single thread - the GUI thread (the …