The glass blur effect is actually disabled in VMware and other unaccelerated graphics devices. You can disable it on intel/AMD/nvidia too, the setting is in the accessibility part of system preferences.

They've just removed the last remnants of pure 2D acceleration support in Yosemite, it's HW-accelerated OpenGL or nothing now. They also changed the timing of screen updates, which locks some drivers at 8FPS. Finally, the rounded corners on windows seem to be broken in the software renderer.

Before you go blaming VMWare etc. for not offering an OpenGL driver: Apple doesn't document those APIs at all, there aren't even headers files. They don't even officially support writing a graphics device driver at all (according to DTS), but they provide enough source code so you can figure out how to do so, albeit not providing 3D acceleration.

At some point I'm going to attempt shimming CoreGraphics or wherever it ends up to fake 3D acceleration by proxying the OpenGL calls to the host without using a real driver.

Have you used iOS 7.1+ on an iPhone 5/5S or better? I haven't noticed any performance issues since iOS 7.0. I think they've optimized the hell out of the blur effect at this point.

Bugs and generally poor software quality, however? Yes.

As a general experience it's 'good enough' on the iphone 5. It would of been cut otherwise. But for example if you compare starting and using any app on iOS 6 vs iOS 7, you'll find out that the exact same executable is far faster on iOS 6 than iOS 7.

They said at wwdc that the blur effect took a lot of 'optimization' work. You don't have a lot of control over how it works and in iOS 7 you had to hack it in by using a UIToolbar vs applying it to a UIView in iOS 8. If you have any view with a significant amount of the blur effect on screen, the animation speed will slow down considerably in the simulator.

They use the effect everywhere in iOS and I bet it does contribute to a decent chunk of performance reduction.