I use a oneliner that parallelizes with "-P$(nproc)"
find "$DIR" -name '*.flac' -type f -print0 |xargs -0 -n1 -P$(nproc) flac -st
"-n1" means a new "flac" command is spawned for every file,
increasing granularity and thus ability to parallelize.
"nproc" is in newer GNU coreutils, and "-P" and "-0" require GNU xargs;
you can just use the number of cores you have if you don't have "nproc".
Btw, if_then_else: is your name because you're a programmer or a fan of the album by The Gathering? (I am both :)