Generally they are in the same league. I would expect that SBCL is faster in some benchmarks and applications, but slightly slower in real life Lisp application

Generally they are in the same league. I would expect that SBCL is faster in some benchmarks and applications, but slightly slower in real life Lisp applications. Allegro CL and LispWorks have been used for some very large commercial applications - where the application developers demanded special optimizations for those over the years. The implementors actually don't put too much attention to benchmark performance - but application developers pay for real-life performance. I would expect that SBCL might have an advantage in some areas where it's easier to write fast code, because of its type inference and compiler hints. That's very useful. Some benchmarks on smaller machines like Macs and ARM-boards. http://lispm.de/lisp/benchmarks.html http://lispm.de/lisp/benchmarks.html