Why OpenGL state changes very slow on VirtualBox? - opengl

Question

I'm on Linux host and using a Windows guest.
I'm creating the OpenGL context with SDL, and I just draw 1000 objects in different positions, each object is just 6 vertices and 3 lines, just a 3D cross.
I'm using vertex and index buffers and GLSL shaders. It doesn't do anything special: it binds the buffers and sets the vertex attrib pointers, set the matrix and draws the elements.
It renders the scene in 2 seconds, if I hoist the buffer binding and attribute setting outside the loop it renders in 200ms, if I remove glUniformMatrix4fv that sets the matrix due to the updated positions it'll render about 10ms, though I only see 1 object and thousand other is just overdrawn on it.
On Linux and Windows host the same thing renders on stable 60FPS.
OpenGL games like OpenArena run on 60FPS in VirtualBox...
Is buffer binding and uniform setting a slow operation in OpenGL in general?
Does anyone has experience testing 3D programs on VirtualBox?
Update: added some code, error checking removed for clarity:
void drawStuff()
{
GLfloat projectView[16];
int ms;
RenderingContext rc; /*< Nothing special contains the currently bound render object.*/
glClearColor(0, 0, 0, 1);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
createViewMatrix(
viewMatrix,
&viewedObject->attitude.k,
&viewedObject->attitude.j,
&viewedObject->pos
);
multiplyMatrix(projectView, viewMatrix, projMatrix); /*< Combine projection and view matrices. */
/* Draw 10×10×10 grid of 3D crosses. One cross is 6 vertices and 3 lines. */
bindRenderObject(&rc, &cross); /*< This binds buffers and sets up vertex attrib arrays. It's very slow if I put it into the loop*/
{
int i, j, k;
for (i = -5; i < 5; i++)
{
for (j = -5; j < 5; j++)
{
for (k = -5; k < 5; k++)
{
createTranslationMatrix(modelMatrix, i * 10, j * 10, k * 10);
multiplyMatrix(combinedMatrix, modelMatrix, projectView);
glUniformMatrix4fv(renderingMatrixId, 1, GL_FALSE, combinedMatrix); /*< This is slow for some reason.*/
drawRenderObject(&rc); /*< This is just a call to glDrawElements. No performance bottleneck here at all. */
}
}
}
}
/* Draw some UI. */
glDisable(GL_DEPTH_TEST);
/* ... */
glEnable(GL_DEPTH_TEST);
SDL_GL_SwapBuffers();
}