You were rigth, when PyMC is imported there is this warning,
WARNING (pytensor.configdefaults): g++ not detected! PyTensor will be unable to compile C-implementations and will default to Python. Performance may be severely degraded. To remove this warning, set PyTensor flags cxx to an empty string.
WARNING (pytensor.tensor.blas): Using NumPy C-API based implementation for BLAS functions.
But I installed it using conda forge as described in the link you provided. I didn’t install JAX nor Nutpie support. What could be the issue?