Frozen threads?

gistfile1.p6

use GTK::Simple;

my GTK::Simple::App $app .= new(title => "Test");
$app.set_content(
	GTK::Simple::VBox.new(
		my $input = GTK::Simple::Entry.new(),
		my $output = GTK::Simple::Label.new(text => "ready"),
	),
);

$input.changed.stable(1).tap: -> $more { 
	my $then = now;
	say "Got $more.text()";
	#Waste some cycles here:
	my $z = [+] (^500).map({ (^10_000).pick }).grep(*.is-prime);
	
	#Thought it might because I was updating the label. But it wasn't. You can comment the next line out.	
	$output.text = ($z%100) ~ ('a'...'z').pick(6).join;
	say "Took " ~ now - $then;
};


$app.run;