If I understand this correctly, this puts an upper bound on the computational ability of a Dyson sphere surrounding a star.
Stuff like: https://en.wikipedia.org/wiki/Margolus%E2%80%93Levitin_theor... https://en.wikipedia.org/wiki/Bremermann%27s_limit
The Landauer limit is dependent on temperature, though. If you fast forward the universe a little bit to let the CMB cool down, even irreversible computing can get pretty efficient in theory.