And for something a bit different
This just writes out to STDOUT with username and filename as it finds the file. This may be quicker if you have a lot of users scattered since you only do one pass on the filesystem. Then you have to process the file, which may eat that savings...

mirod & DWS have valid comments and the only thing they didn't mention that I would is to check if passwd gets opened correctly.

Update:
jeffa points out that checking if /etc/passwd is opened might be pointless. You've got more problems if that fails. Such as you may be on a different OS, but then why this program? I guess I'm trained to check my opens.

  use File::Find;
  use File::stat;
  use strict;
  use warnings;

  my $dir_search = "/home/u1";  #I'd rather do a cmd line arg
  my $min_uid = 1000;           #but for this...
  my %hash;

  open PASSWD, '/etc/passwd' or die "Could not open /etc/passwd";

  while (<PASSWD>){
    my ($user, $toss , $uid) = split(/:/);

    $hash{$uid} = $user if $uid > $min_uid;
  }
  close(PASSWD);
  my @uids = keys %hash;

  File:find (\&wanted, $dir_search);
  exit;

sub wanted {
  return if (-d $_); #Let's just list files

  my $st = stat($_);
  next unless defined($st); #Diagnostics may be wanted here

  if (grep($st->uid, @uids)) {
    print $hash{$st->uid}, "\t", $File::Find::name, "\n" ;
  }
}

# on slices
# Vynce suggested: my ($user, undef, $uid) = split(/:/);
# jeffa this: my ($user,$uid) = (split(/:/))[0,2];
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