No problem. No, I was referring to rendering graphics on the CPU, ie. the standard way of doing this. Using hardware acceleration can offload some tasks like rendering huge amounts of lines to the GPU. Note that this can be achieved automatically to some degree by using the OpenGLContext class.
The specifics of building audio plugin infrastructures is not something I’ve found litterature on, and has been a trial and error process. If you’re interested in getting deeper in the DSP and mathemathics, there are loads of free litterature on the subject, for instance:
http://www.dspguide.com/pdfbook.htm
https://ccrma.stanford.edu/~jos/ (specifically “Introduction to digital filters”)
http://www.ece.rutgers.edu/~orfanidi/intro2sp/orfanidis-i2sp.pdf
These are general and cover fundamentals in detail.