C# DataGridView Summary Row

I’ve been working a lot lately on a project, which gave me some gray hairs! Mostly because I needed a datagridview with a summary row located in the bottom of the grid, but I found a project trying to solve that exact problem. However it is not very thorough and has some performance issues, but it gave me a nice start, which I’ve used to create a faster and better(but not much!) implementation. I’ve also made it possible to show the average in the summary row and fixed some bugs.

I’ll share the source with you people later, when I’ve cleaned up the code and corrected some of the bugs I know exists in it.