https://www.youtube.com/watch?v=mVbDzTM21BQ

http://en.wikibooks.org/wiki/Optimizing_C%2B%2B/Code_optimization
http://en.wikibooks.org/wiki/Optimizing_C++/Code_optimization/Faster_operations

https://mattmccutchen.net/bigint/
https://code.google.com/p/infint/
http://cpp-bigint.sourceforge.net/
https://gmplib.org/