The basic purpose of the GPL and most other open source licenses is to ensure code transparency and promote sharing of code modifications. Proprietary software companies do not like this too much for they feel that it will force them to give away their intellectual property.
Yet these self same companies have jumped all over microsofts C# because it is, according to microsoft, the next best thing since sliced bread!
The problem is not the actual programming, nor is it the speed or program size. The problem is….DaDah TaTah….releasing it to market. Unlike a proper executable or programming language, C# is an interpreted language just like BASIC or Java. That C# executable you have there is really to all extents and purposes a fancy ZIP file with all of your source code inside.