First off, I'm programming a game. Currently in the render function there are two calls to two different functions. One renders some text, one renders sprites.
On my computer (AMD Phenom(tm) II X4 955 Processor (4 CPUs), ~3.2GHz, 4096MB RAM DDR2, NVIDIA GeForce GTX 285) I have a render speed of ~2200 FPS when rendering around 200 sprites and about 100 FPS when rendering about 14,500.
I'm using a vector to store the information of each object I'm rendering and using one sprite with many draw calls.
VS2008 release mode with full optimization for C++. I know I've heard left and right don't optimize prematurely, but at this point, it's running great for me, but not so well on certain computers.
I can't imagine changing vectors out for arrays since I'm pushing and pulling things from the vector every frame, in an indeterminable method. Nearly randomly.
I've tried floats and doubles and the speed is no different.
Would it be different using DirectDraw rather than DirectX and the Sprite Render method? Since I've no idea the differences between DirectDraw and DirectX, I'm not 100% what I should be thinking about that.
The game runs fine on average computers, but what I'm comparing my game to is Touhou. Touhou runs at 60 FPS on the weakest computer I've tried, but my game won't run faster than 36~42 FPS. I can't imagine what I'm doing wrong, being so new to DirectX and C++.
Any assistance in this matter would be great, unfortunately I won't be around for awhile to add information or answers questions.
You need a profiler.
There's some good performance advice in the responses, but it doesn't matter. Trying to optimize a program without a profiler is like trying to write a program without a compiler. Do not guess, measure.
Now with that said, profiling graphics code is an infamous pain in the neck, and there aren't (to my knowledge) any good, free tools to help with it. So never mind that for now: start with an ordinary CPU profiler, and find out which of your calls is really taking up all your time.