The present invention discloses a speech processing solution that utilizes an original speech recognition grammar in a speech recognition system to perform speech recognition operations for multiple recognition instances. Instance data associated with the recognition operations can be stored. A replacement grammar can be automatically generated from the stored instance data, where the replacement grammar is a statistical language model grammar. The original speech recognition grammar, which can be a grammar-based language model grammar or a statistical language model grammar, can be selectively replaced with the replacement grammar. For example when tested performance for the replacement grammar is better than that for the original grammar, the replacement grammar can replace the original grammar.