Hi Sébastien,
  I’m curious, was a plugin (e.g., PPAPI) or Chrome native client ever considered?  Such as how Unity encapsulates it’s projects in a NPAPI plugin.  Most of these SDKs are C/C++ so it could theoretically circumvent the need for Web Audio API and also use some of Pd’s native code. 
  Anyway, I’m quite impressed with what you’ve done with WebPd.    
-Rob

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Robert Esler
Co-Director
urbanSTEW