When $*DEBUG set, show Widget.full-refresh timing info

Author: japhb

lib/Terminal/Widgets/Widget.rakumod

@@ -342,9 +342,15 @@ class Terminal::Widgets::Widget
 
     #| Fully refresh this widget and optionally force a print
     method full-refresh(Bool:D :$print = True) {
+        my $debug = +($*DEBUG // 0);
+        my $t0    = now;
+
         self.clear-frame;
         self.draw-frame;
         self.composite(:$print);
+
+        note sprintf("  ⏱️  Full Refresh {self.gist-name}: %.3fms", 1000 * (now - $t0))
+             if $debug;
     }
 
     #| Clear the frame and set it all-dirty (so it requires composite)