The difference in performance is explained by the capabilities of the algorithms used by each parser library.

The Earley algorithm can parse any context-free grammar while Chevrotain appears to be restricted to the LL(k) class of grammars. Earley is O(n³) in the worst case but it performs better with more restricted classes of context-free grammars. Even if given the same grammar, Earley will still incur the cost of generality, a cost which LL(k) parsers don't have to pay.