Question

I”m experiencing random framerate increases when I run my game (developed using c#/XNA 4.0) on the PC. These increases are causing a stuttering affect during gameplay. It usually happens when the game starts up and is just frequent enough to be annoying.

For example – my FPS counter will jump from 62 to 85 (causing a slight stutter) then back to 62 and stay consistently between 62/63 FPS for three minutes and then jump to 78 then go back to 62/63 again. It’s rare for the FPS to actually drop below 60.

Any ideas of what is going on?

Edit – Added my FPS code below (02.06.2013)

namespace Game
{
    class FPSDebuggerFont : Font
    {

        //int totalScore;

        //FramesPerSecond (FPS) debug variables
        int totalFrames = 0;
        int fps = 0;
        int elpaseMilliseconds = 1000;
        string fpsText;

        public FPSDebuggerFont(SpriteFont scoreFont, String text, Vector2 pos, Color color, float scale, float layerDepth)
            : base(scoreFont, text, pos, color, scale, layerDepth)
        {
        }

        public void FPSTime(GameTime gameTime)
        {
            //Algorithm for FPS debugging
            elpaseMilliseconds -= (float)gameTime.ElapsedGameTime.Milliseconds;
            if (elpaseMilliseconds < 0)
            {
                //FPS debugg info
                fps = totalFrames;
                elpaseMilliseconds = 1000;
                totalFrames = 0;
            }

        }

        public override void Update(GameTime gameTime)
        {
            FPSTime(gameTime);

        }

        public override void Draw(GameTime gameTime, SpriteBatch sB)
        {
            totalFrames++;
            fpsText = "Frames Per Second: " + fps;

            sB.DrawString(scoreFont, fpsText, pos, color, 0, Vector2.Zero, scale, SpriteEffects.None, layerDepth);

        }
    }
}

For clarification purposes, I’m not sure how I can add anymore code regarding this without adding my entire project. But I can certainly add more information; along with my Game class I have two other classes (SpriteManager, FontManager) using the GameComponent functionality of XNA, each containing their own Load Content, Update, and Draw methods, example below;

public class SpriteManager : Microsoft.Xna.Framework.DrawableGameComponent
{
    //Manager code
} 

public class FontManager : Microsoft.Xna.Framework.DrawableGameComponent
{
    //Manager code
}

Hopefully this additional information helps.

End Edit

Answer 1

It could be anything without seeing the code. It shouldn’t cause any stuttering problems though as long as you’re using gameTime.ElapsedGameTime in your movement calculations.

For example:

sprite.Location += sprite.Velocity * (float)gameTime.ElapsedGameTime.TotalSeconds;