I read:

• dsp cycles: if i have a complex calculation that requires several pd objects, will it take several dsp cycles (one for each object) or is it calculated at once. eg, if i have an abstraction that does 100 calculations (one after another) when i send a bang, would it take 100 dsp cycles?

no, every ~ object's dsp routine is called exactly once per dsp_cycle, if one or several objects fail at doing there calculations on the sample- buffer in that time you will hear dropouts.

• how can you switch of the calculation of some generators / subpatches / patches? (i would really need this in my patches)

[switch~]

• abstractions vs externals: i suppose externals would be faster (if you want you could even write your external in the assembler language of your machine), but require more ram (more code, maybe larger classes)... is this correct?

well externals should usually be faster (since they are compiled) and there are things one simply cannot solve with the internal objects.

HTH

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