my %files;
sub files_wanted {
  my $raw_file = $File::Find::name;
  if ( -f ) {
    my ($volume,$directories,$file) = File::Spec->splitpath($raw_file)
+; #update from a prior suggestion.
    my $file_size = -s $raw_file;
    push @{$files{"$file ($file_size bytes)"}}, $raw_file;
  }
}
[download]

While you are in the "wanted" subroutine that File::Find::find runs, the full path is in the $File::Find::name variable and the file name only is in the $_ variable so there is no need to use File::Spec->splitpath() to do something that File::Find::find has already done for you.    Also, you are still using stat on the same file twice when it would be more efficient to do it only once.