I'm trying to continuously update a widget to show numbers h:m:s:ms which are returned from a method in another api linked to Qt. That api generally uses a control loop for the method which returns the time elapsed since a method was started. I finally got QLabel to update using my own signal, and repaint, but the time displayed is very slow; much slower than realtime. The float value for the elapsed time looks fine when shown in the console.

Is there a better way to go about this to get an h:m:s:ms display which receives values from another api's method, or is it possible to display updated text in Qt without using a widget? I'm not sure what is causing the slow down.

Qt Code: 
  1. //myclass.h
  2.       #ifndef MYCLASS_H
  3.       #define MYCLASS_H
  4.       #include <QWidget>
  5.  
  6.       #include "API.hpp"
  7.       class QLabel;
  8.  
  9.             class myClass : public QWidget
  10.             Q_OBJECT
  11.             public:
  12.                 QLabel *mylabel;
  13.                 double timeVal;
  14.                 int runapi();
  15.             public slots:
  16.                 void setNum (double num);
  17.             signals:
  18.                 void mySignal(double newnum);
  19.             private:
  20.                 API *myapi;
  21.             -----
  22.            //myclass.cpp
  23.  
  24.            #include "myclass.h"
  25.             myClass::myClass()
  26.             {
  27.                 myapi = new API;
  28.                 mylabel = new QLabel;
  29. 		connect (this, SIGNAL ( mySignal(double) ), mylabel, SLOT ( setNum(double) ) );
  30.             }
  31.             int myClass::runapi()
  32.             {
  33. 		while ( myapi->myintreturn() ==0 )
  34. 		{
  35.                 timeVal->myapi->mymethodelapsedtime();  //returns double
  36.                 mylabel->setNum(timeVal);
  37. 	        mylabel->repaint();
  38. 		}
  39.             }
  40.             void myClass::setNum (double num)
  41.             {
  42.             emit mySignal(num);
  43.             }
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