Ubuntu 14.04 LTS: perl-tk - slower than 12 LTS

Below is a simlified perl-tk code which runs much slower with the new ubuntu 14.04.

The file "bugrun.pl":

#!/usr/bin/perl -w

use strict;
use Tk;
require Tk::TextUndo;
require Tk::Pane;
require Tk::BrowseEntry;

my %s;
my %n;

my $mw=new MainWindow;
my $form3;
my $but2;

my $form1=$mw->Frame();
$form1->grid(-row=>1,-column=>1,-sticky=>"w");

my $but1=$form1->Button(-text=>"Query",-command=>\&mk1);
$but1->grid(-row=>1,-column=>5);
sub mk1 {
 my $r;
 foreach $r (1..500) {
  $s{fra}{$r}=$form3->Entry(-width=>6,-textvariable=>\$n{fra}{$r},-state=>"readonly",-bd=>1);
  $s{fra}{$r}->grid(-row=>$r,-column=>1);
  $s{inv}{$r}=$form3->Checkbutton(-text=>"",-variable=>\$n{inv}{$r});
  $s{inv}{$r}->grid(-row=>$r,-column=>2);
  $s{val}{$r}=$form3->Entry(-width=>4,-textvariable=>\$n{val}{$r},-justify=>"r");
  $s{val}{$r}->grid(-row=>$r,-column=>3);
  $s{com}{$r}=$form3->Entry(-width=>56,-textvariable=>\$n{com}{$r});
  $s{com}{$r}->grid(-row=>$r,-column=>4);
  $s{fil}{$r}=$form3->Entry(-width=>2,-textvariable=>\$n{fil}{$r},-state=>"readonly");
  $s{fil}{$r}->grid(-row=>$r,-column=>5);
  $s{fla}{$r}=$form3->Entry(-width=>2,-textvariable=>\$n{fla}{$r});
  $s{fla}{$r}->grid(-row=>$r,-column=>6);
  $s{par}{$r}=$form3->Entry(-width=>2,-textvariable=>\$n{par}{$r});
  $s{par}{$r}->grid(-row=>$r,-column=>7);
  $s{epa}{$r}=$form3->Entry(-width=>9,-textvariable=>\$n{epa}{$r},-state=>"readonly");
  $s{epa}{$r}->grid(-row=>$r,-column=>8);
 }
}
my $form2=$mw->Frame();
$form2->grid(-row=>6,-column=>1);
$form3=$mw->Scrolled("Frame",-scrollbars=>"ose",-width=>650,-height=>408,-sticky=>"nw");
$form3->grid(-row=>2,-column=>1,-sticky=>"nw");
my $form41=$mw->Frame();
$form41->grid(-row=>3,-column=>1,-sticky=>"w");
my $form42=$mw->Frame();
$form42->grid(-row=>4,-column=>1,-sticky=>"w");
my $form43=$mw->Frame();
$form43->grid(-row=>5,-column=>1,-sticky=>"w");
MainLoop;

__END__

In "xterm":
 ./bugrun.pl
Closing the window with "x", system waits;
moving mouse on gvim-window creates the warning in "xterm" window:
 (gvim:8148): IBUS-WARNING **: Process Key Event failed: Timeout was reached.

The same run but breaking with Ctrl-C - no problems with IBUS.