Question

I’ve seen plenty of posts about the simulator running slow, but my problem is different.

I ran my app with instruments and saw that in the device, the app uses about 8mb of live memory when the app is running. In the simulator the live memory is about 50MB, and I have no idea why this is.

This causes the simulator to lag and I need it to run smooth so i can take a nice screen capture video of my app.

Any ideas?

Answer 1

There are a number of steps in the OpenGL ES 1.1/2.0 pipeline that are done in software when running on the simulator (as the Mac GPUs are plain OpenGL) but are hardware accelerated when running on the device (hence it actually running faster on the device).

From the documentation:

Important: Rendering performance of OpenGL ES in Simulator has no
relation to the performance of OpenGL ES on an actual device.
Simulator provides an optimized software rasterizer that takes
advantage of the vector processing capabilities of your Macintosh
computer. As a result, your OpenGL ES code may run faster or slower in
iOS simulator (depending on your computer and what you are drawing)
than on an actual device. Always profile and optimize your drawing
code on a real device and never assume that Simulator reflects
real-world performance.

This definitely explains the speed discrepancy, might also explain the extra memory taken up when running in the simulator.