diff --git a/source/frontends/qapple/qapple.cpp b/source/frontends/qapple/qapple.cpp
index d96b06b6..2bfa5f44 100644
--- a/source/frontends/qapple/qapple.cpp
+++ b/source/frontends/qapple/qapple.cpp
@@ -135,11 +135,10 @@ QApple::QApple(QWidget *parent) :
     myEmulatorWindow = mdiArea->addSubWindow(myEmulator, Qt::CustomizeWindowHint | Qt::WindowTitleHint | Qt::WindowMinMaxButtonsHint);
     myEmulatorWindow->setWindowTitle(g_pAppTitle);
 
-    myMSGap = 10;
+    myMSGap = 5;
 
     initialiseEmulator();
 
-    myCurrentGap = myMSGap;
     startEmulator();
 }
 
@@ -149,27 +148,28 @@ void QApple::closeEvent(QCloseEvent *)
     uninitialiseEmulator();
 }
 
-void QApple::timerEvent(QTimerEvent *)
+void QApple::on_timer()
 {
+    const qint64 elapsed = myElapsedTimer.restart();
     const double fUsecPerSec        = 1.e6;
-    const UINT nExecutionPeriodUsec = 1000 * myMSGap;
+    const UINT nExecutionPeriodUsec = 1000 * elapsed;
 
     const double fExecutionPeriodClks = g_fCurrentCLK6502 * ((double)nExecutionPeriodUsec / fUsecPerSec);
     const DWORD uCyclesToExecute = fExecutionPeriodClks;
 
     const bool bVideoUpdate = false;
-    const DWORD uActualCyclesExecuted = CpuExecute(uCyclesToExecute, bVideoUpdate);
-    g_dwCyclesThisFrame += uActualCyclesExecuted;
 
-    if (g_dwCyclesThisFrame >= dwClksPerFrame)
+    do
     {
-        g_dwCyclesThisFrame -= dwClksPerFrame;
-        myEmulator->redrawScreen();
+        const DWORD uActualCyclesExecuted = CpuExecute(uCyclesToExecute, bVideoUpdate);
+        g_dwCyclesThisFrame += uActualCyclesExecuted;
+        if (g_dwCyclesThisFrame >= dwClksPerFrame)
+        {
+            g_dwCyclesThisFrame -= dwClksPerFrame;
+            myEmulator->redrawScreen();
+        }
     }
-
-    // 0 means run as soon as possible (i.e. no pending events)
-    const int nextGap = DiskIsSpinning() ? 0 : myMSGap;
-    setNextTimer(nextGap);
+    while (DiskIsSpinning());
 }
 
 void QApple::stopTimer()
@@ -181,20 +181,11 @@ void QApple::stopTimer()
     }
 }
 
-void QApple::setNextTimer(const int ms)
-{
-    if (ms != myCurrentGap)
-    {
-        stopTimer();
-        myCurrentGap = ms;
-        myTimerID = startTimer(myCurrentGap, Qt::PreciseTimer);
-    }
-}
-
 void QApple::on_actionStart_triggered()
 {
     // always restart with the same timer gap that was last used
-    myTimerID = startTimer(myCurrentGap, Qt::PreciseTimer);
+    myTimerID = startTimer(myMSGap, Qt::PreciseTimer);
+    myElapsedTimer.start();
     actionPause->setEnabled(true);
     actionStart->setEnabled(false);
 }
@@ -253,7 +244,6 @@ void QApple::on_actionDisk_2_triggered()
 void QApple::on_actionReboot_triggered()
 {
     startEmulator();
-    setNextTimer(myMSGap);
 }
 
 void QApple::on_actionBenchmark_triggered()
@@ -261,3 +251,8 @@ void QApple::on_actionBenchmark_triggered()
     VideoBenchmark([this]() { myEmulator->redrawScreen(); });
     on_actionReboot_triggered();
 }
+
+void QApple::timerEvent(QTimerEvent *)
+{
+    on_timer();
+}
diff --git a/source/frontends/qapple/qapple.h b/source/frontends/qapple/qapple.h
index ccda5b04..1c510d33 100644
--- a/source/frontends/qapple/qapple.h
+++ b/source/frontends/qapple/qapple.h
@@ -4,6 +4,7 @@
 #include "ui_qapple.h"
 
 #include <QFileDialog>
+#include <QElapsedTimer>
 
 class Emulator;
 
@@ -37,19 +38,20 @@ private slots:
 
     void on_actionBenchmark_triggered();
 
+    void on_timer();
+
 private:
 
-    void setNextTimer(const int ms);
     void stopTimer();
     void insertDisk(const int disk);
 
     QFileDialog myDiskFileDialog;
 
+    QElapsedTimer myElapsedTimer;
     QMdiSubWindow * myEmulatorWindow;
     Emulator * myEmulator;
 
     int myMSGap;
-    int myCurrentGap;
 
     int myTimerID;
 };