Random framerate increases in XNA

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

You first need to figure out what code is causing this, then you can ask specific questions, on how to solve your problem. Without the actual code all we can do is speculate on what could cause the problem. — Security Hound
How are you counting FPS? What are your vsync and fixed-update-rate settings? — Andrew Russell
Added my FPS code to the original question. I am not utilizing a vsync and fixed-update-rate settings, maybe this is my problem? — Bilbo

itsme86 itsme86 · Accepted Answer · 2013-02-05T17:04:47

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;

Random framerate increases in XNA

1 Answers