If you have a patch that is too slow for desktop, there's no way a 180MHz microcontroller would be able to run it. There are a few other considerations:
OWL doesn't run the same PuraData that you run on desktop - this is not possible, because it would require an actual OS. It uses a compiler called "Heavy" that generates C++ code from PD that getss compiled to run on microcontroller.
Not every object is available when compiled on Heavy, you can find more info in our PD docs
Some parts of generated code would be using optimized maths calls, this improves performance (sometimes considerably). This may also cause some differences in patch output, but those optimization can be disabled in compiled code.
I don't use PD myself, but I've seen some impressive stuff done it in for OWL, i.e. you can check out generative Fascination Machine patches in patch library.
You can try your own patches in web patcher, once you've got something that works you can ask here for someone to test it. Then you'll get feedback about its performance/usability.