In practice you can always make a program take less space if it can use more time, or take less time if it can use more space; the guiltless perfection you seek

In practice you can always make a program take less space if it can use more time, or take less time if it can use more space; the guiltless perfection you seek does not exist. I feel like PEG parsing can be fast and space-efficient, but I haven't seen an existence proof yet.