You can control the choice of algorithms used by changing these option variables.

If the size of the objects being generated by a grammar specification is large, the start-up time can be improved by installing the generating function package gfun, and setting the variable `combstruct/usegfun` to true. The default value of `combstruct/usegfun` is false.

The variable `combstruct/method` controls the algorithm used to generate products in a grammar specification.

If 'combstruct/method' is set to 'optimized', for every product in the specification, the system tries each method for the first 30 sizes, and selects the best one based on the results. The default method is 'boustrophedon'.

For references that explain the algorithms, see the combstruct package.