[SDL] SDL_RenderCopy very slow on Lumia 520 Windows Phone 8.1

John Girvin hello at nivrig.com
Wed Jan 27 14:28:12 PST 2016


I made a simple "BunnyMark" style benchmark with SDL2.0.4 based on
SDL_RenderCopy-ing as many moving 32x32 sprites to the screen as
possible while maintaining 60fps. An iPod 4 can manage about 1100 such
sprites before slowing down, but when I tried the same code on a Lumia
520 it could barely manage 10% of that. The Lumia benchmarks a little
faster than an iPod 5 in general, so something seems off here.

The device was running the latest Windows Phone 8.1 and everything was
built from source in release mode.

I confirmed SDL was using the D3D11 render path, but I also got the same
ballpark result when using the OpenGLES renderer via ANGLE.

I ran a similar Cocos2DX benchmark that could animate 2200 sprites @
60fps on the same device, I believe with an OpenGLES render path.

This is a profiling run of the SDL code:
D3D11_UpdateVertexBuffer is the major CPU hog. I don't know anything
about D3D programming so I stopped there.

Main File:

Complete VS2015 Community Solution:

Am I doing something stupid here (other than running contrived
benchmarks, obv) ?
Any suggestions?


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