diff --git a/docshell/test/navigation/test_bug430723.html b/docshell/test/navigation/test_bug430723.html
index 91339926fa54..ee9da6d160fe 100644
--- a/docshell/test/navigation/test_bug430723.html
+++ b/docshell/test/navigation/test_bug430723.html
@@ -63,7 +63,7 @@ var step1 =function() {
   
   // Navigate down and up.
   is(testWindow.document.body.scrollTop, 0,
-     "Page1: Ensure we scrollpane is at the top before we start scrolling.");
+     "Page1: Ensure the scrollpane is at the top before we start scrolling.");
   testWindow.addEventListener("scroll", function () {
     testWindow.removeEventListener("scroll", arguments.callee, true);
     isnot(testWindow.document.body.scrollTop, 0,
@@ -91,11 +91,11 @@ var step2 =function() {
 
   // Scroll around a bit.
   is(testWindow.document.body.scrollTop, 0,
-     "Page2: Ensure we scrollpane is at the top before we start scrolling.");
+     "Page2: Ensure the scrollpane is at the top before we start scrolling.");
 
   var count = 0;
   testWindow.addEventListener("scroll", function () {
-    if (++count < 4) {
+    if (++count < 2) {
       SimpleTest.executeSoon(function () { sendKey('DOWN', testWindow); });
     } else {
       testWindow.removeEventListener("scroll", arguments.callee, true);
diff --git a/layout/base/nsPresShell.cpp b/layout/base/nsPresShell.cpp
index 24d3ccdc1964..82a11bcec879 100644
--- a/layout/base/nsPresShell.cpp
+++ b/layout/base/nsPresShell.cpp
@@ -2471,8 +2471,8 @@ PresShell::ScrollLine(bool aForward)
   nsIScrollableFrame* scrollFrame =
     GetFrameToScrollAsScrollable(nsIPresShell::eVertical);
   if (scrollFrame) {
-    // Scroll 2 lines at a time to improve scrolling speed.
-    PRInt32 lineCount = 2;
+    PRInt32 lineCount = Preferences::GetInt("toolkit.scrollbox.verticalScrollDistance",
+                                            NS_DEFAULT_VERTICAL_SCROLL_DISTANCE);
     scrollFrame->ScrollBy(nsIntPoint(0, aForward ? lineCount : -lineCount),
                           nsIScrollableFrame::LINES,
                           nsIScrollableFrame::SMOOTH);
diff --git a/layout/generic/nsGfxScrollFrame.cpp b/layout/generic/nsGfxScrollFrame.cpp
index 50edad41cc2f..ff2c0f87f099 100644
--- a/layout/generic/nsGfxScrollFrame.cpp
+++ b/layout/generic/nsGfxScrollFrame.cpp
@@ -3237,7 +3237,8 @@ nsGfxScrollFrameInner::ReflowFinished()
     nsPoint scrollPos = GetScrollPosition();
     // XXX shouldn't we use GetPageScrollAmount/GetLineScrollAmount here?
     if (vScroll) {
-      const double kScrollMultiplier = 3;
+      const double kScrollMultiplier = Preferences::GetInt("toolkit.scrollbox.verticalScrollDistance",
+                                                           NS_DEFAULT_VERTICAL_SCROLL_DISTANCE);
       nscoord fontHeight = GetLineScrollAmount().height * kScrollMultiplier;
       // We normally use (scrollArea.height - fontHeight) for height
       // of page scrolling.  However, it is too small when
diff --git a/layout/generic/nsIScrollableFrame.h b/layout/generic/nsIScrollableFrame.h
index c87a86266c93..8e33ff48f507 100644
--- a/layout/generic/nsIScrollableFrame.h
+++ b/layout/generic/nsIScrollableFrame.h
@@ -47,6 +47,8 @@
 #include "nsPresContext.h"
 #include "nsIFrame.h" // to get nsIBox, which is a typedef
 
+#define NS_DEFAULT_VERTICAL_SCROLL_DISTANCE 3
+
 class nsBoxLayoutState;
 class nsIScrollPositionListener;
 
diff --git a/modules/libpref/src/init/all.js b/modules/libpref/src/init/all.js
index 7e11e1480f1e..a05808e7008a 100644
--- a/modules/libpref/src/init/all.js
+++ b/modules/libpref/src/init/all.js
@@ -297,6 +297,8 @@ pref("toolkit.autocomplete.richBoundaryCutoff", 200);
 
 pref("toolkit.scrollbox.smoothScroll", true);
 pref("toolkit.scrollbox.scrollIncrement", 20);
+// Make sure to update NS_DEFAULT_VERTICAL_SCROLL_DISTANCE if changing this default.
+pref("toolkit.scrollbox.verticalScrollDistance", 3);
 pref("toolkit.scrollbox.clickToScroll.scrollDelay", 150);
 
 // Telemetry