The arbitrary difference between a "toy" and a "tool" is the completeness of the proposed solution. Correctness, ease of use and documentation concerns could co

The arbitrary difference between a "toy" and a "tool" is the completeness of the proposed solution. Correctness, ease of use and documentation concerns could come well before execution speed. I agree that writing an interpreter for an existing language (e.g. Python) one would want to match the performance of existing interpreters and thus would need to use the techniques you mention.