There is not enough information in the O.P. Does this happen in the same way all the time or only at certain times? Does it only happen when an object using the texture is in motion? If the problem varies, then it might be useful to know when it is at the worst. Does the problem persist when you have no texture in use? Does the test with no texture cause any change in this stuttering. You should run tests to determine the texture file coding is the source of the issue.
If C# is not coded correctly, then it is prone in some cases to cause a game to stutter as memory data is handled automatically but clumsily. If well coded, then C# can allow auto memory management to run smoothly but takes experience in when and how to code parenting and other points.
Bottom line is that your coding is in need of correction or optimization somewhere and the texture is not the cause. Coding may allow almost any image file, certainly all the more common ones. Sure, try Bitmap, but you would be better as a programmer to understand how two or more different types of images files may be coded in your game.
Edited by 3Ddreamer, 05 April 2013 - 08:46 PM.
Personal life and your private thoughts always effect your career. Research is the intellectual backbone of game development and the first order. Version Control is crucial for full management of applications and software. The better the workflow pipeline, then the greater the potential output for a quality game. Completing projects is the last but finest order.
by Clinton, 3Ddreamer