I did some profiling the other day and I found that drawing my gui over my 3d scene increased my frametime by up to 30%. I'm using GWEN for my gui but it allows you to write a custom renderer which I did. I used the same terrible techniques as the sample renderer but was able to squeeze out a little more performance by better integrating it into my engine which removed a few OpenGL calls. The problem with the renderer is that the way it works is that I basically get to derive a renderer class and rewrite a DrawTexturedRect function and that is the only way I can get geometry. In the sample implementation (and mine) It places two triangles to form a quad in a buffer on the cpu side when everything is finished drawing or the buffer is full it calls a flush function which uploads the buffer to the gpu and draws it, then the buffer is emptied. The problem is that this happens every frame and I have no way of knowing whether the geometry has actually changed between frames so I have no choice but to do everything all over again. So I was thinking of ways to change this awful setup while only being allowed to use DrawTexturedRect and I thought about instancing a single 1x1 quad (everthing is a quad with the same texcoords) and then scaling and translating it in the vertex shader. But unfortunately instanced rendering is only core in OpenGL 3.1+ and my minimum is GL 2.1 support where it is available as an extension (but probably not on intel cards). So my question boils down to is it faster to draw individual quads (one draw call per quad) that are already in the gpu memory or to use the terrible buffering solution? any other general GUI drawing advice would be appreciated as well.