Not my experience with Nemo (in A plea for int overflow checking as the default - #46 by Olof_Salberger the Nemo integers did not improve the speed).
Anyway, you see now why I said that the generalized GAP “numbers” which are union of everything from Int to
Cyclotomics are beyond my capacity to implement in the current state of Julia. I really need to have an
example Union{Int,BigInt} to look at so I understand how to extend it.