diff --git a/src/gui/fluxviewercontrol.cc b/src/gui/fluxviewercontrol.cc
index 10895350..878af9a8 100644
--- a/src/gui/fluxviewercontrol.cc
+++ b/src/gui/fluxviewercontrol.cc
@@ -13,8 +13,9 @@ DECLARE_COLOUR(FOREGROUND, 0, 0, 0);
 DECLARE_COLOUR(FLUX, 64, 64, 255);
 DECLARE_COLOUR(RECORD, 255, 255, 255);
 
-const int BORDER = 10;
+const int BORDER = 4;
 const int MINIMUM_TICK_DISTANCE = 10;
+const double RENDER_LIMIT = 3000.0;
 
 FluxViewerControl::FluxViewerControl(wxWindow* parent,
     wxWindowID id,
@@ -50,15 +51,48 @@ void FluxViewerControl::SetFlux(std::shared_ptr<const TrackFlux> flux)
 	auto size = GetSize();
 	_nanosecondsPerPixel = (double)_totalDuration / (double)size.GetWidth();
 
-	ResizeScrollbar();
+	UpdateScale();
 	Refresh();
 }
 
-void FluxViewerControl::ResizeScrollbar()
+void FluxViewerControl::UpdateScale()
 {
 	auto size = GetSize();
 	nanoseconds_t thumbSize = size.GetWidth() * _nanosecondsPerPixel;
 	_scrollbar->SetScrollbar(_scrollPosition/1000, thumbSize/1000, _totalDuration/1000, thumbSize/2000);
+
+	int totalPixels = (_totalDuration / _nanosecondsPerPixel) + 1;
+	if ((totalPixels != _densityMap.size()) && (_nanosecondsPerPixel > RENDER_LIMIT))
+	{
+		_densityMap.resize(totalPixels);
+		std::fill(_densityMap.begin(), _densityMap.end(), 0.0);
+
+		int i = 0;
+		for (const auto& trackdata : _flux->trackDatas)
+		{
+			FluxmapReader fmr(*trackdata->fluxmap);
+			while (!fmr.eof())
+			{
+				unsigned ticks;
+				if (!fmr.findEvent(F_BIT_PULSE, ticks))
+					break;
+
+				int fx = fmr.tell().ns() / _nanosecondsPerPixel;
+				_densityMap.at(i + fx)++;
+			}
+			i += trackdata->fluxmap->duration() / _nanosecondsPerPixel;
+		}
+
+		double max = *std::max_element(_densityMap.begin(), _densityMap.end());
+		for (auto& d : _densityMap)
+			d /= max;
+	}
+}
+
+static int interpolate(int lo, int hi, float factor)
+{
+	float range = hi - lo;
+	return lo + range*factor;
 }
 
 void FluxViewerControl::OnPaint(wxPaintEvent&)
@@ -128,6 +162,20 @@ void FluxViewerControl::OnPaint(wxPaintEvent&)
 				tickCount++;
 			}
 
+			if (x <= 0)
+				dc.DrawText(
+					fmt::format("{}us", (int)(_scrollPosition / 1000LL)),
+					{ BORDER, t3y + ch2/2 }
+				);
+
+			if ((x+fw) >= w)
+			{
+				wxString text = fmt::format(
+					"{}us", (int)((_scrollPosition + (w * _nanosecondsPerPixel)) / 1000LL));
+				auto size = dc.GetTextExtent(text);
+				dc.DrawText(text, { w - size.GetWidth() - BORDER, t3y + ch2/2 });
+			}
+
 			/* Sector blocks. */
 
 			for (const auto& sector : trackdata->sectors)
@@ -155,26 +203,55 @@ void FluxViewerControl::OnPaint(wxPaintEvent&)
 			/* Flux chart. */
 
 			dc.SetPen(FLUX_PEN);
-			dc.DrawLine({x, t4y}, {x+fw, t4y});
-			FluxmapReader fmr(*trackdata->fluxmap);
-			while (!fmr.eof())
+			if (_nanosecondsPerPixel > RENDER_LIMIT)
 			{
-				int event;
-				unsigned ticks;
-				fmr.getNextEvent(event, ticks);
+				/* Draw using density map. */
 
-				int fx = fmr.tell().ns() / _nanosecondsPerPixel;
-
-				if (event & F_BIT_INDEX)
+				dc.SetPen(*wxTRANSPARENT_PEN);
+				for (int fx = 0; fx < _densityMap.size(); fx++)
 				{
-					dc.SetPen(INDEX_SEPARATOR_PEN);
-					dc.DrawLine({x+fx, 0}, {x+fx, h});
-					dc.SetPen(FLUX_PEN);
+					if (((x+fx) > 0) && ((x+fx) < w))
+					{
+						float density = _densityMap[fx];
+						wxColour colour(
+							interpolate(BACKGROUND_COLOUR.Red(), FLUX_COLOUR.Red(), density),
+							interpolate(BACKGROUND_COLOUR.Green(), FLUX_COLOUR.Green(), density),
+							interpolate(BACKGROUND_COLOUR.Blue(), FLUX_COLOUR.Blue(), density));
+						wxBrush brush(colour);
+						dc.SetBrush(brush);
+						dc.DrawRectangle({x+fx, t4y - ch2}, {1, ch});
+					}
 				}
-
-				if (event & F_BIT_PULSE)
-					dc.DrawLine({x+fx, t4y - ch2}, {x+fx, t4y + ch2});
 			}
+			else
+			{
+				/* Draw discrete pulses. */
+
+				FluxmapReader fmr(*trackdata->fluxmap);
+				while (!fmr.eof())
+				{
+					int event;
+					unsigned ticks;
+					fmr.getNextEvent(event, ticks);
+
+					int fx = fmr.tell().ns() / _nanosecondsPerPixel;
+					if (((x+fx) > 0) && ((x+fx) < w))
+					{
+						if (event & F_BIT_INDEX)
+						{
+							dc.SetPen(INDEX_SEPARATOR_PEN);
+							dc.DrawLine({x+fx, 0}, {x+fx, h});
+							dc.SetPen(FLUX_PEN);
+						}
+
+						if (event & F_BIT_PULSE)
+							dc.DrawLine({x+fx, t4y - ch2}, {x+fx, t4y + ch2});
+					}
+				}
+			}
+
+			dc.SetPen(FLUX_PEN);
+			dc.DrawLine({x, t4y}, {x+fw, t4y});
 		}
 
 		x += w;
@@ -193,7 +270,7 @@ void FluxViewerControl::OnMouseWheel(wxMouseEvent& event)
 		_nanosecondsPerPixel *= 1.2;
 	_scrollPosition -= x * _nanosecondsPerPixel;
 
-	ResizeScrollbar();
+	UpdateScale();
 	Refresh();
 }
 
diff --git a/src/gui/fluxviewercontrol.h b/src/gui/fluxviewercontrol.h
index 5f63b1b6..d4d53058 100644
--- a/src/gui/fluxviewercontrol.h
+++ b/src/gui/fluxviewercontrol.h
@@ -21,7 +21,7 @@ public:
 	void SetFlux(std::shared_ptr<const TrackFlux> flux);
 
 private:
-	void ResizeScrollbar();
+	void UpdateScale();
 
 private:
 	void OnPaint(wxPaintEvent&);
@@ -34,6 +34,7 @@ private:
 	nanoseconds_t _scrollPosition;
 	nanoseconds_t _totalDuration;
 	double _nanosecondsPerPixel;
+	std::vector<float> _densityMap;
     wxDECLARE_EVENT_TABLE();
 };