The ASF+SDF Meta-Environment is an interactive language development environment whose main application areas are definition and implementation of domain-specific languages, generation of program analysis and transformation tools, and production of software renovation tools. It uses conditional rewrite rules to define the dynamic semantics and other tool-oriented aspects of languages, so the effectiveness of the generated tools is critically dependent on the quality of the rewrite rule implementation. The ASF+SDF rewrite rule compiler generates C code, thus taking advantage of C's portability and the sophisticated optimization capabilities of current C compilers as well as avoiding potential abstract machine interface bottlenecks. It can handle large (10,000+ rule) language definitions and uses an efficient run-time storage scheme capable of handling large (1,000,000+ node) terms. Term storage uses maximal subterm sharing (hash-consing), which turns out to be more effective in the case of ASF+SDF than in Lisp or SML. Extensive benchmarking has shown the time and space performance of the generated code to be as good as or better than that of the best current rewrite rule and functional language compilers.