Bremermann's limit, named after Hans-Joachim Bremermann, is a limit on the maximum rate of computation that can be achieved in a self-contained system in the material universe. Wikipedia

Highest possible rate of computation in this universe Wikidata

The maximum computational speed of a self-contained system in the material universe, derived from Einstein's mass-energy equivalency and the Heisenberg uncertainty principle: it is approximately 1.36 × 1050 bits per second per kilogram. This value is important in designing cryptographic algorithms that can never be cracked by brute force. Wiktionary