So, it appears to be behaving normally? Isn’t it generally a good idea to use the least number of CPU draw calls as possible? This begs the question: does the decision to use instancing depend on the number of draw calls for a single object type, or all calls for all objects. For example, if I have 1000 different types of objects in the scene, each having 1 or more instances, isn’t better to instance every call?
The issue with frame rate is frustrating. I agree that frame time is more informative, but the general populace seems obsessed with frame rate, usually 30 or more as a benchmark. Even if I work with frame time as a measure of efficiency, in the end I feel obliged to report the efficiency as frame rate. 
In either case, I’m simply trying to keep from using unnecessary steps in order to make my program more efficient (and more importantly learn as I go). It seems bizarre that such a simple scene should be so hard for the graphics card to produce. This computer can tackle games that are far more graphical than the simple scene I made.
By lighting, I’m using a split between vertex and fragment shader, as shown here:
Vertex Shader
#version 330 core
layout (location = 0) in vec3 position;
layout (location = 1) in vec3 normal;
layout (location = 2) in vec2 tex_coords;
layout (location = 3) in vec3 tangent;
layout (location = 4) in vec3 bitangent;
layout (location = 5) in mat4 instanceMatrix;
#define MAX_NUMBER_OF_SHADER_LIGHTS 6
uniform vec4 LightPosition[MAX_NUMBER_OF_SHADER_LIGHTS];
uniform int LightEnabled[MAX_NUMBER_OF_SHADER_LIGHTS];
uniform mat4 mProjection;
uniform mat4 mView;
out vec2 UV;
out vec3 position_cs;
out vec3 eyedirection_cs;
out vec3 eyedirection_ts_normal;
out vec3 lightdirection_cs[MAX_NUMBER_OF_SHADER_LIGHTS];
//out vec3 lightdirection_ts[MAX_NUMBER_OF_SHADER_LIGHTS];
out vec3 lightdirection_ts_normal[MAX_NUMBER_OF_SHADER_LIGHTS];
void main(void)
{
mat4 mModelView = mView * instanceMatrix;
////////////////////////////////////////////////////////////////////
position_cs = (mModelView * vec4(position,1.0)).xyz;
/*export*/ eyedirection_cs = -position_cs;
// model to camera = ModelView
vec3 normal_cs = mat3(mModelView) * normal;
vec3 tangent_cs = mat3(mModelView) * tangent;
vec3 bitangent_cs = mat3(mModelView) * bitangent;
mat3 TBN = transpose(mat3(tangent_cs,bitangent_cs,normal_cs));
/*export*/ vec3 eyedirection_ts = TBN * eyedirection_cs;
/*export*/ eyedirection_ts_normal = normalize(eyedirection_ts);
////////////////////////////////////////////////////////////////////
for( int i = 0 ; i < MAX_NUMBER_OF_SHADER_LIGHTS ; i++ )
{
if(LightEnabled[i] > 0)
{
/////////////////////////////////////////////////////////////////////////////////////
vec3 lightposition_cs = LightPosition[i].xyz;
/*export*/ lightdirection_cs[i] = normalize(lightposition_cs + eyedirection_cs);
/*export*/ vec3 lightdirection_ts = TBN * lightdirection_cs[i];
/*export*/ lightdirection_ts_normal[i] = normalize(lightdirection_ts);
/////////////////////////////////////////////////////////////////////////////////////
}
}
UV = tex_coords;
gl_Position = mProjection * vec4(position_cs,1);
}
// Fragment shader
#version 330 core
#define MAX_NUMBER_OF_SHADER_LIGHTS 6
uniform vec4 LightPosition[MAX_NUMBER_OF_SHADER_LIGHTS];
uniform vec4 LightColor[MAX_NUMBER_OF_SHADER_LIGHTS];
uniform int LightEnabled[MAX_NUMBER_OF_SHADER_LIGHTS];
uniform float Ambient_Intensity;
uniform sampler2D tex; // texture bound in slot 0
uniform sampler2D spec; // specular bound in slot 1
uniform sampler2D norm; // normal bound in slot 2
in vec2 UV;
in vec3 position_cs;
in vec3 eyedirection_cs;
in vec3 eyedirection_ts_normal;
in vec3 lightdirection_cs[MAX_NUMBER_OF_SHADER_LIGHTS];
in vec3 lightdirection_ts_normal[MAX_NUMBER_OF_SHADER_LIGHTS];
out vec4 color;
void main (void)
{
vec4 MaterialDiffuseColor = texture2D( tex, UV.xy );
if(MaterialDiffuseColor.a == 0)
discard;
// color = vec4(MaterialDiffuseColor.xyz,1.0f);
// return;
color = vec4(0.0f,0.0f,0.0f,1.0f);
vec4 MaterialAmbientColor = vec4(MaterialDiffuseColor.xyz * Ambient_Intensity,1.0f);
vec4 MaterialSpecularColor = texture2D( spec, UV.xy );
vec3 TextureNormal_ts = normalize(texture2D( norm, vec2(UV.x,UV.y) ).rgb*2.0 - 1.0);
for( int i = 0 ; i < 1 ; i++ )
{
if(LightEnabled[i] > 0)
{
float distance = length( vec3(LightPosition[i]) - position_cs );
// Cosine of the angle between the normal and the light direction,
float cosTheta;
if(gl_FrontFacing)
cosTheta = clamp( dot( TextureNormal_ts,lightdirection_ts_normal[i] ), 0,1 );
else
cosTheta = clamp( dot( -TextureNormal_ts,lightdirection_ts_normal[i] ), 0,1 );
// Direction in which the triangle reflects the light
vec3 R = reflect(-lightdirection_ts_normal[i],TextureNormal_ts);
float cosAlpha = clamp( dot( eyedirection_ts_normal,R ), 0,1 );
color += MaterialAmbientColor + (LightColor[i] / (distance * distance)) * (MaterialDiffuseColor * cosTheta + MaterialSpecularColor * pow(cosAlpha,16));
}
}
}
Edit: BTW, I’m using instanced matrices. In your experience, does switching to using position vectors and quaternions make enough difference in performance to warrant the switch?