From: janburse@fastmail.fm   
      
   Ok, I found another Prolog system which is slower than   
   SWI-Prolog, newest version, but still can do 9^(9^9)   
   in reasonable time:   
      
       ECLiPSe Constraint Logic Programming System [kernel threads]   
       Version 7.0 #36 (x86_64_nt), Sun Jan 28 10:18 2018   
      
       [eclipse 1]: _ is 9^(9^9).   
       Yes (20.73s cpu)   
      
   Maybe we can speculate they use the same library as   
   sage, their timing is very similar. Its open source, so   
   I could lookup the source, to see what they are using.   
      
   Ralf Stephan schrieb:   
    > The Sage version is 8.3.beta6 here but there shouldn't be much   
   difference to 8.2 with that computation, I think. I also confirmed with   
   'sage -callgrind' that most of the time (95.6%) is spent in   
   libgmp.so.23.0.3 in object files starting with "fft...".   
    >   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)