Export time N12 vs N13

I’ve realised that N13 takes more time to export audio than N12. Same project (a mix of a dubbing session for a 50’ runtime with about 60 tracks and eight instances of Reverence plus other inserts) takes about 15’ to render to a stereo file in N12, while N13 takes about 24 minutes.
N13 seems to run smoother in general except closing projects.
Both measures have been done with same machine (Mac Studio M1 Max 64GB RAM) running Monterey in Rosetta mode (project contains MPEX edits and I want to preserve them).
Anyone has checked something similar?

The fact is buffer was setting to 256 in N13 instead 1024 in N12. Now, with 1024 the export time is the same.