I noticed with -force64 its rather slow myself but without that flag its as efficient as it should be, anyhow this is the first revision of a kernel/dyld that can use 64bit binaries simultaneously as 32 bit on amd so i guess it can take a bit time until its as reliable as it is on a intel cpu

Also, my terminal gets bombarded with:
dyld: shared cached file was build against a different libSystem.dylib, ignoring cache

not a big deal though

I guess I should do some benchmarks myself to confirm the slow downs, working with anything coreaudio with -force64 at the moment is just too glitchy.