Nothing in the code you showed should take even a millisecond, so the problem isn't directly in the code you showed. You might test this in a couple ways. The simplest thing to do is to put a messagebox saying pretty nearly anything as the first line in that method. That will tell you whether the slowdown is occuring before or after that code. You can also use a Stopwatch to time that code by starting the stopwatch before the code, then stopping it after the code and looking at the elapsedMilliseconds. If it turns out that the code you have shown is where the slowdown is happening, then it is most likely some kind of side effect, such as altering a control could be triggering some events on the control.