I am rendering 2.7 million vertices.when I don't use transparency(means opacity is 1.0) for my vertices and Alpha blending remains enabled then my fragment function does not take much time and FPS is 60. as soon as I give opacity 0.5 for each vertex then Fragment function becomes very slow and my FPS is coming down to 23. please anyone give me any hint what could be the issue? I profiled app using Xcode's GPU debugger and Xcode does not show any performance issue.
I am attaching two screen shots of performance timeline and performance counters taken from Xcode Metal Debugger tool. as we can see render command encoder is taking 45 .16 ms in ScreenShot-1 and that is because of fragment function which takes same time 45.15 ms that we can see in ScreenShot-2.
please see attached screens shots and let me know if someone sees any issue with any performance counter and where should I investigate?