Performance updates (#9082)

* Avoid creation of curve legend widgets during construction of a multi plot
* Make sure default z-value is correct to avoid expensive Qwt updates
* Avoid duplicate plot updates
* Do not create internal Qwt legend by default
* RFT import: Avoid expensive method throwing exception if no data is found

ApplicationLibCode/ProjectDataModel/RimPlot.cpp

@@ -76,7 +76,7 @@ QWidget* RimPlot::createViewWidget( QWidget* parent /*= nullptr */ )
     RiuPlotWidget* plotWidget = doCreatePlotViewWidget( parent );
 
     updateWindowVisibility();
-    plotWidget->scheduleReplot();
+    if ( showWindow() ) plotWidget->scheduleReplot();
 
     return plotWidget;
 }