diff --git a/OscarWatch.Tests/Performance/PassPolarPlotRenderCacheTests.cs b/OscarWatch.Tests/Performance/PassPolarPlotRenderCacheTests.cs
new file mode 100644
index 0000000..1b841bf
--- /dev/null
+++ b/OscarWatch.Tests/Performance/PassPolarPlotRenderCacheTests.cs
@@ -0,0 +1,97 @@
+// Feature: startup-io-rendering-optimisation, Task 8.2: PassPolarPlotControl render cache unit tests
+
+using Avalonia.Media;
+using FsCheck;
+using FsCheck.Xunit;
+using OscarWatch.Controls;
+
+namespace OscarWatch.Tests.Performance;
+
+/// <summary>
+/// **Validates: Requirements 8.1, 8.3**
+///
+/// Verifies that <see cref="RenderResourceCache.GetRoundCapPen"/> returns the same object
+/// reference on repeated calls, and that the returned pen has the expected LineCap/LineJoin properties.
+/// </summary>
+public class PassPolarPlotRenderCacheTests
+{
+    /// <summary>
+    /// GetRoundCapPen returns the same reference for the same colour and thickness on repeated calls.
+    /// </summary>
+    [Property(MaxTest = 100)]
+    public bool GetRoundCapPen_returns_same_reference(byte a, byte r, byte g, byte b, PositiveInt thicknessRaw)
+    {
+        var color = Color.FromArgb(a, r, g, b);
+        var thickness = (double)thicknessRaw.Get / 10.0;
+        var cache = new RenderResourceCache();
+
+        var pen1 = cache.GetRoundCapPen(color, thickness);
+        var pen2 = cache.GetRoundCapPen(color, thickness);
+
+        return ReferenceEquals(pen1, pen2);
+    }
+
+    /// <summary>
+    /// GetRoundCapPen returns a pen with LineCap = Round and LineJoin = Round.
+    /// </summary>
+    [Property(MaxTest = 100)]
+    public bool GetRoundCapPen_has_round_cap_and_join(byte a, byte r, byte g, byte b, PositiveInt thicknessRaw)
+    {
+        var color = Color.FromArgb(a, r, g, b);
+        var thickness = (double)thicknessRaw.Get / 10.0;
+        var cache = new RenderResourceCache();
+
+        var pen = cache.GetRoundCapPen(color, thickness);
+
+        return pen.LineCap == PenLineCap.Round && pen.LineJoin == PenLineJoin.Round;
+    }
+
+    /// <summary>
+    /// GetRoundCapPen returns a pen with the correct thickness and brush colour.
+    /// </summary>
+    [Property(MaxTest = 100)]
+    public bool GetRoundCapPen_has_correct_thickness_and_color(byte a, byte r, byte g, byte b, PositiveInt thicknessRaw)
+    {
+        var color = Color.FromArgb(a, r, g, b);
+        var thickness = (double)thicknessRaw.Get / 10.0;
+        var cache = new RenderResourceCache();
+
+        var pen = cache.GetRoundCapPen(color, thickness);
+        var brush = pen.Brush as SolidColorBrush;
+
+        if (brush is null)
+            return false;
+
+        return pen.Thickness == thickness && brush.Color == color;
+    }
+
+    /// <summary>
+    /// Clear() removes round-cap pen entries so the next call creates a fresh pen.
+    /// </summary>
+    [Fact]
+    public void Clear_removes_round_cap_pens()
+    {
+        var cache = new RenderResourceCache();
+        var color = Colors.Red;
+
+        var pen1 = cache.GetRoundCapPen(color, 2.5);
+        cache.Clear();
+        var pen2 = cache.GetRoundCapPen(color, 2.5);
+
+        Assert.NotSame(pen1, pen2);
+    }
+
+    /// <summary>
+    /// Different colours produce different pen references (not shared incorrectly).
+    /// </summary>
+    [Fact]
+    public void GetRoundCapPen_different_colors_different_pens()
+    {
+        var cache = new RenderResourceCache();
+
+        var pen1 = cache.GetRoundCapPen(Colors.Red, 2.5);
+        var pen2 = cache.GetRoundCapPen(Colors.Blue, 2.5);
+
+        Assert.NotSame(pen1, pen2);
+    }
+}
diff --git a/OscarWatch/Controls/FormattedTextCache.cs b/OscarWatch/Controls/FormattedTextCache.cs
index d4aeb69..b8f4959 100644
--- a/OscarWatch/Controls/FormattedTextCache.cs
+++ b/OscarWatch/Controls/FormattedTextCache.cs
@@ -23,6 +23,15 @@ internal sealed class FormattedTextCache
     /// Recreates brushes if the palette colours have changed.
     /// </summary>
     public FormattedText Get(string name, double fontSize, UiPalette palette)
+    {
+        return Get(name, fontSize, palette.MapLabelForeground);
+    }
+
+    /// <summary>
+    /// Returns a cached FormattedText for the given name, font size, and explicit foreground colour.
+    /// Creates the text on first request; returns the cached instance on subsequent calls with the same key.
+    /// </summary>
+    public FormattedText Get(string name, double fontSize, Color foreground)
     {
         var key = (name, fontSize);
         if (!_cache.TryGetValue(key, out var text))
@@ -33,7 +42,7 @@ public FormattedText Get(string name, double fontSize, UiPalette palette)
                 FlowDirection.LeftToRight,
                 GetTypeface(),
                 fontSize,
-                GetLabelBrush(palette))
+                new SolidColorBrush(foreground))
             {
                 MaxTextWidth = 120
             };
diff --git a/OscarWatch/Controls/PassPolarPlotControl.cs b/OscarWatch/Controls/PassPolarPlotControl.cs
index 0b4c455..396ae22 100644
--- a/OscarWatch/Controls/PassPolarPlotControl.cs
+++ b/OscarWatch/Controls/PassPolarPlotControl.cs
@@ -21,6 +21,7 @@ public class PassPolarPlotControl : ThemeAwareControl
 
     private PassPolarPlotHitTest.HoverPoint? _hoverPoint;
     private readonly RenderResourceCache _renderCache = new();
+    private readonly FormattedTextCache _textCache = new();
 
     public static readonly StyledProperty<PassPolarPlotData?> PlotDataProperty =
         AvaloniaProperty.Register<PassPolarPlotControl, PassPolarPlotData?>(nameof(PlotData));
@@ -82,7 +83,7 @@ public override void Render(DrawingContext context)
         var local = new Rect(0, 0, w, h);
         var (cx, cy, plotRadius) = GetPlotGeometry(w, h);
 
-        context.FillRectangle(new SolidColorBrush(palette.SkyPlotBackground), local);
+        context.FillRectangle(_renderCache.GetBrush(palette.SkyPlotBackground), local);
         DrawHorizonDisk(context, cx, cy, plotRadius, palette);
         DrawElevationRing(context, cx, cy, plotRadius, 30, palette.SkyPlotRing30, 1);
         DrawElevationRing(context, cx, cy, plotRadius, 60, palette.SkyPlotRing60, 1);
@@ -103,11 +104,7 @@ public override void Render(DrawingContext context)
                 continue;
 
             var color = segment.IsSunlit ? palette.SunlightTimeline : EclipsePathColor;
-            var pen = new Pen(new SolidColorBrush(color), 2.5)
-            {
-                LineCap = PenLineCap.Round,
-                LineJoin = PenLineJoin.Round
-            };
+            var pen = _renderCache.GetRoundCapPen(color, 2.5);
 
             var first = segment.Points[0];
             if (!SkyPlotControl.TryAzElToPoint(cx, cy, plotRadius, first.AzimuthDeg, first.ElevationDeg, out var prev))
@@ -162,16 +159,16 @@ private static (double Cx, double Cy, double PlotRadius) GetPlotGeometry(double
         return (cx, cy, plotRadius);
     }
 
-    private static void DrawHorizonDisk(DrawingContext context, double cx, double cy, double plotRadius, UiPalette palette)
+    private void DrawHorizonDisk(DrawingContext context, double cx, double cy, double plotRadius, UiPalette palette)
     {
         var disk = new Rect(cx - plotRadius, cy - plotRadius, plotRadius * 2, plotRadius * 2);
         context.DrawEllipse(
-            new SolidColorBrush(palette.SkyPlotBackground),
-            new Pen(new SolidColorBrush(palette.SkyPlotBorder), 1.5),
+            _renderCache.GetBrush(palette.SkyPlotBackground),
+            _renderCache.GetPen(palette.SkyPlotBorder, 1.5),
             disk);
     }
 
-    private static void DrawElevationRing(
+    private void DrawElevationRing(
         DrawingContext context,
         double cx,
         double cy,
@@ -182,16 +179,16 @@ private static void DrawElevationRing(
         bool dashed = false)
     {
         var r = (90.0 - Math.Clamp(elevationDeg, 0, 90)) / 90.0 * plotRadius;
-        var pen = new Pen(new SolidColorBrush(color), thickness);
-        if (dashed)
-            pen.DashStyle = DashStyle.Dash;
+        var pen = dashed
+            ? _renderCache.GetDashedPen(color, thickness)
+            : _renderCache.GetPen(color, thickness);
 
         context.DrawEllipse(null, pen, new Rect(cx - r, cy - r, r * 2, r * 2));
     }
 
-    private static void DrawAzimuthSpokes(DrawingContext context, double cx, double cy, double plotRadius, UiPalette palette)
+    private void DrawAzimuthSpokes(DrawingContext context, double cx, double cy, double plotRadius, UiPalette palette)
     {
-        var pen = new Pen(new SolidColorBrush(palette.SkyPlotSpoke), 1);
+        var pen = _renderCache.GetPen(palette.SkyPlotSpoke, 1);
         for (var az = 0; az < 360; az += 45)
         {
             if (!SkyPlotControl.TryAzElToPoint(cx, cy, plotRadius, az, 0, out var spokeEnd))
@@ -201,7 +198,7 @@ private static void DrawAzimuthSpokes(DrawingContext context, double cx, double
         }
     }
 
-    private static void DrawCardinalLabels(DrawingContext context, double cx, double cy, double plotRadius, UiPalette palette)
+    private void DrawCardinalLabels(DrawingContext context, double cx, double cy, double plotRadius, UiPalette palette)
     {
         DrawLabel(context, "N", cx, cy - plotRadius - 14, palette);
         DrawLabel(context, "S", cx, cy + plotRadius + 4, palette);
@@ -223,21 +220,15 @@ private void DrawHoverMarker(DrawingContext context, double cx, double cy, doubl
             HoverMarkerRadiusPx * 2,
             HoverMarkerRadiusPx * 2);
         context.DrawEllipse(
-            new SolidColorBrush(HoverMarkerFill),
-            new Pen(new SolidColorBrush(HoverMarkerOutline), 2),
+            _renderCache.GetBrush(HoverMarkerFill),
+            _renderCache.GetPen(HoverMarkerOutline, 2),
             rect);
-        context.DrawEllipse(null, new Pen(Brushes.White, 1.5), rect);
+        context.DrawEllipse(null, _renderCache.GetPen(Colors.White, 1.5), rect);
     }
 
-    private static void DrawLabel(DrawingContext context, string text, double x, double y, UiPalette palette)
+    private void DrawLabel(DrawingContext context, string text, double x, double y, UiPalette palette)
     {
-        var ft = new FormattedText(
-            text,
-            System.Globalization.CultureInfo.CurrentCulture,
-            FlowDirection.LeftToRight,
-            new Typeface(FontFamily.Default, FontStyle.Normal, FontWeight.SemiBold),
-            12,
-            new SolidColorBrush(palette.SkyPlotLabel));
+        var ft = _textCache.Get(text, 12, palette.SkyPlotLabel);
         context.DrawText(ft, new Point(x, y));
     }
 
diff --git a/OscarWatch/Controls/RenderResourceCache.cs b/OscarWatch/Controls/RenderResourceCache.cs
index 84ed668..76727fe 100644
--- a/OscarWatch/Controls/RenderResourceCache.cs
+++ b/OscarWatch/Controls/RenderResourceCache.cs
@@ -11,6 +11,7 @@ internal sealed class RenderResourceCache
     private readonly Dictionary<Color, SolidColorBrush> _brushes = new();
     private readonly Dictionary<(Color Color, double Thickness), Pen> _pens = new();
     private readonly Dictionary<(Color Color, double Thickness), Pen> _dashedPens = new();
+    private readonly Dictionary<(Color Color, double Thickness), Pen> _roundCapPens = new();
 
     /// <summary>
     /// Returns a cached SolidColorBrush for the given colour, creating one on first request.
@@ -56,6 +57,26 @@ public Pen GetDashedPen(Color color, double thickness)
         return pen;
     }
 
+    /// <summary>
+    /// Returns a cached Pen with LineCap = Round and LineJoin = Round for the given colour and thickness.
+    /// Used for pass path segments that need rounded line endings.
+    /// </summary>
+    public Pen GetRoundCapPen(Color color, double thickness)
+    {
+        var key = (color, thickness);
+        if (!_roundCapPens.TryGetValue(key, out var pen))
+        {
+            pen = new Pen(GetBrush(color), thickness)
+            {
+                LineCap = PenLineCap.Round,
+                LineJoin = PenLineJoin.Round
+            };
+            _roundCapPens[key] = pen;
+        }
+
+        return pen;
+    }
+
     /// <summary>
     /// Clears all cached brushes and pens. Called when track states composition changes
     /// or the colour palette changes (theme switch).
@@ -65,5 +86,6 @@ public void Clear()
         _brushes.Clear();
         _pens.Clear();
         _dashedPens.Clear();
+        _roundCapPens.Clear();
     }
 }