Valentin Albillo's "Boldly Going... Going Back to the roots" now for the HP-41 !

[Vincent Weber]

This is a simulator, not an emulator.

You just can't do performances comparisons with the original, it's like comparing apples to oranges.
Besides, I usually don't trust simulators, especially when dealing with advanced math features as in the 15C, as I have no ideas of how they were coded.
Exceptions include free42/plus42 (outstanding compatibility) and Willy's simulators on ios (high quality).