Actually the performance is pretty good. My iPad Pro is basically running LispWorks as fast as my 2015 Macbook. It's faster than other ARM systems I've seen, too.
Interesting. I might give this a shot. Do you know if CFFI stuff works -- so that I could use eg. cl-opengl or cl-sdl2 -- if you somehow statically link stuff together? That's what I do w/ LuaJIT for example. Or maybe LispWorks has its own OpenGL bindings, not sure.