gtk-update-icon-cache 3.20.8-0ubuntu2 (amd64 binary) in ubuntu yakkety

 gtk-update-icon-cache creates mmap()able cache files for icon themes.
 .
 GTK+ can use the cache files created by gtk-update-icon-cache to avoid a lot
 of system call and disk seek overhead when the application starts. Since the
 format of the cache files allows them to be mmap()ed shared between multiple
 applications, the overall memory consumption is reduced as well.