simple question about opengl es

[TechnoEagle]

I currently have 20 uibuttons on the screen. When you tap one, it disappears and is replaced by a particle explosion (using particle emitter from project on this page: Particle Designer ).

I am experiencing serious problems with performance, and after running tests, it seems the lag is caused by the call to glClear(GL_COLOR_BUFFER_BIT);

I am confused since glClear() is a common OpenGL function and I would not have thought I would experience issues.

I would appreciate any advice on how to speed up/optimize calls to glClear(). I am a beginner with OpenGL and OpenGL ES, so I might be making a simple mistake.