FrameBufferObject::AttachTexture prints the message
"PERFORMANCE WARNING:
Redundant bind of texture ..."
when attaching a different cube map face.
For example, the sequence
fbo.AttachTexture(GL_TEXTURE_CUBE_MAP_NEGATIVE_X, _textureID, GL_COLOR_ATTACHMENT0_EXT);
...
fbo.AttachTexture(GL_TEXTURE_CUBE_MAP_POSITIVE_Z, _textureID, GL_COLOR_ATTACHMENT0_EXT);
is identified as redundant but it is not.