I noticed horrible performance on mobile: both Android and iOS.
Without any playing events, FMOD takes 7-10% CPU! With 5 events at the same time it increases to 25-30% CPU time…
Tested devices: iPhone 6 and NVIDIA Shield Tablet K1
This is unnaceptable and if it won’t be fixed I should consider move to Wwise 
Profiler: http://oi63.tinypic.com/2wpv2mb.jpg
What cpu usage are you seeing in the Xcode profiler alone i.e. without fmod studio attached ?
( if that’s what you are doing - can’t say since i’ve never used fmod studio profiler )
I tried also Xcode Profiler, Tegra Profiler and UE4 profiler. Everywhere it reports similar CPU usage…
Its quite possible the CPU has lowered itself into a very low CPU speed as not much else is happening, this is not an FMOD specific issue. If you can put it into a developer mode where the cpu is running at full capacity you will notice this is not going to be anywhere near this high.
Please refer here for more information http://www.fmod.org/documentation/#content/generated/platform_ios/performance_reference.html
The FMOD mixer can mix 32 voices in as little as 1.1% on a 5S, which is a generation behind the 6.