could be a number of things. Could be the fact that the computer is slow Perhaps the anti virus software is kicking in causing it to slow down Could be because the code you have written at the point where it appears to be slow, is inefficient Tried building it under release mode than debug mode to see if it will speed it up The release mode removes all debugging information and optimizes the assembly, causing it to enhance performance.

Do you also do Console.Write() from your WinForm app If so, this does dramatically slow down the application....

can you show us the code you think that is slowing down