Hi, I develop musicals apps for iOS, Android devices using pd.

The biggest obstacle I find when developing with pd is the lack of performance.

I find it almost impossible to build a simple subtractive polyphonic synth because using a single biquad based lowpass filter(Maelstorm's) already eats up half of CPU usage on my iPad2.

I don't really understand why pd is so heavy considering it is written in low level C.

My question is, if I write external for certain purpose(i.e filters), will it be helpful to reduce the CPU usage then using multiple pd objects?

Or will it be ultimately better to use another audio library that performs better than pd CPU wise? If so, please recommend me one.

Since you provided no patch, it is quite difficult to guess reasons for a high CPU-Usage.

But generally: In my Patches i implement switches to disable parts of the GUI i need for monitoring. This saves me a lot of performance, since GUI-Updates are quite heavy on the CPU.

Agreed. It's also common to have a envelope follower on a sub patch output which is then patched to a switch~, thereby disabling the sub page when the output reaches a certain threshold.