1. A method for qualifying changes to an instruction set in source code comprising: receiving text in a code editor as an edit to source code of a computer program; and, responding to the edit to the source code by: determining an instruction set that was modified as the edit to the source code; querying a data store of code change costs with the instruction set that was modified; retrieving in response to the query a code change cost associated with the instruction set that was modified; displaying in the code editor the retrieved code change cost; committing the instruction set changed; monitoring performance data resulting from an execution of the committed instruction set; and updating the data store of code changes with the performance data resulting from the execution of the committed instruction set including at least one of central processing unit (CPU) usage, path length and response time.