Window 7 slowdown

I’m responsible for maintaining a piece of software ( 3 dimensional modeling )that uses
OpenGL. My primary knowledge is in the computational side of the program and not the graphics interface.

We have had this application in the market for over 10 years and other than OpenGL’s lack of text support, it has run satisfactorly under Windows 98, XP, NT and Vista.

We have just loaded a PC with Windows 7 and the graphic are now refreshing at a snails pace. We just has a customer call in with the same frustration. I’m at a loss as to where to start looking as I don’t see many similar complaints online,

Make sure they have also installed the vendor’s driver as the stock Windows installation likely does not include OpenGL accelerated drivers.

To help the thread move better, can you post the hardware specs, and/or driver revision number you currently have on those machines ?

its running on a 2.13GHz dual core processor with 2G ram.
the video is an NVidia Gforce 8500GT
driver, dated 9/27/09

I enabled OpenGL error checking within my program and no errors were reported.

for an image with 2600 3D vectors
on XP a the screen can refresh 1 to 2 x per second
on Vista64 the screen can refresh in 1-2 seconds
on Windows 7 the screen requires 15-25 seconds to redraw.

( the above isn’t exact as it was done on three different pcs with various hardware )

I enabled OpenGL error checking within my program and no errors were reported.

Beware that GL error reporting can be disabled in the control panel with recent Nvidia drivers ‘to improve performance’.

What calls do you use to draw your “2600 3d vectors” ?
Do you use double buffering ?

void DrawSeg(GLColor *color, char UD, float x, float y,
unsigned long i, bool numbered)
static int count=0;

if (UD == 'D')
if (prevPD)
 // Start new line - written out in pairs
	glVertex2f(prevX, prevY); 
// End line
glVertex2f(x, y); 

// Save this point
prevPD = true;
// Start new list

glNormal3f(0.0f, 0.0f, 1.0f);
glVertex2f(x, y); 

   prevPD = false;
prevX = x;
prevY = y;


If you care a tiny bit about performance, use VBO instead of immediate mode !
“2600 3d vectors” should be very fast, 60+ FPS !

Immediate mode is slow, but that shouldn’t cause his program to refresh slower than before.

When you create a GL context, check the flags and vendor strings returned.
Are you getting back a hardware accelerated context?

finally located the source of the problem, our installer loaded an older version of opengl32.dll into our runtime directory to keep some of our legacy customers happy. Deleting that file has solved the problem.

I had a small program OpenGL, GLUT (gl.h, glut.h) that worked fine on my Windows XP machine in Visual C++ Express. Copied over to my Vista 64 laptop and now compiles OK (after I specifiy correct include folder and lib folder for glut.h and glut.lib) but I get a “glut32.dll” not found when I try to run it.
Then by exploring the forums I learned that I had to move lut32.dll file into C:\Windows\SysWOW64 instead of C:\Windows\System32. Now I don’t get the “glut32.dll not found” error anymore. However, I don’t see any graphics yet, just a black screen, but I bet that has to do with my graphics card and compatibility or lack thereof with OpenGL. My graphic card is Intel GMA HD, can you help me what is the required settings in order to see my graphics…The table below is the OpenGL setting for my graphics card;
Attribute Default Value Other Applicable Values
Asynchronous Flip Off/On Triple Buffering Default/On/Off
Flipping Policy Flip Blit
Depth Buffer Bit Depth Default 16/24 Bit Depth Buffer
Force S3TC Texture Compression Off On
Force FXT1 Texture Compression Off On
Driver Memory Footprint Normal Low/High
Texture Color Depth Desktop Color Depth 16/32 Bits per Texel
Anisotropic Filtering Application Control On/Off