Add an update timer to the progress bar set to 500ms instead of

nothing. STEP Reader is updating the progress bar every time a new
Shape is decoded/transferred and loaded, which is a huge amount
of "interrupt" and slow down drastically the global performance

src/Gui/ProgressBar.cpp

@@ -215,11 +215,14 @@ void Sequencer::setValue(int step)
                 showRemainingTime();
         }
         else {
-            d->bar->setValue(step);
-            if (d->bar->isVisible())
-                showRemainingTime();
-            d->bar->resetObserveEventFilter();
-            qApp->processEvents();
+	    int elapsed = d->progressTime.restart();
+	    if (elapsed > 500) {
+	            d->bar->setValue(step);
+	            if (d->bar->isVisible())
+	                showRemainingTime();
+	            d->bar->resetObserveEventFilter();
+	            qApp->processEvents();
+	    }
         }
     }
 }