diff --git a/binary/src/subscriptLoader.cpp b/binary/src/subscriptLoader.cpp
index 5b3aa483..82769cba 100644
--- a/binary/src/subscriptLoader.cpp
+++ b/binary/src/subscriptLoader.cpp
@@ -523,7 +523,7 @@ dactylUtils::LoadSubScript (const PRUnichar * aURL
 
     nsCAutoString cachePath;
     cachePath.Append("jssubloader/");
-    cachePath.Append(version);
+    cachePath.AppendInt(version);
     if (charset) {
         cachePath.Append("/");
         cachePath.Append(NS_ConvertUTF16toUTF8(
diff --git a/common/content/buffer.js b/common/content/buffer.js
index fab4283e..176c6053 100644
--- a/common/content/buffer.js
+++ b/common/content/buffer.js
@@ -1316,16 +1316,19 @@ var Buffer = Module("buffer", {
      *
      * @param {Element} elem The element to scroll.
      * @param {number|null} left The left absolute pixel offset. If
-     *   null, to not alter the horizontal scroll offset.
+     *      null, to not alter the horizontal scroll offset.
      * @param {number|null} top The top absolute pixel offset. If
-     *   null, to not alter the vertical scroll offset.
+     *      null, to not alter the vertical scroll offset.
      * @param {string} reason The reason for the scroll event. See
-     *  {@link marks.push}. @optional
+     *      {@link marks.push}. @optional
      */
     scrollTo: function scrollTo(elem, left, top, reason) {
         if (~[elem, elem.document, elem.ownerDocument].indexOf(buffer.focusedFrame.document))
             marks.push(reason);
 
+        if (options["scrollsteps"] > 1)
+            return this.smoothScrollTo(elem, left, top);
+
         elem = Buffer.Scrollable(elem);
         if (left != null)
             elem.scrollLeft = left;
@@ -1338,6 +1341,39 @@ var Buffer = Module("buffer", {
                 .redraw();
     },
 
+    /**
+     * Like scrollTo, but scrolls more smoothly and does not update
+     * marks.
+     */
+    smoothScrollTo: function smoothScrollTo(elem, x, y) {
+        let time = options["scrolltime"];
+        let steps = options["scrollsteps"];
+
+        let data = elem;
+        elem = Buffer.Scrollable(elem);
+
+        if (data.dactylScrollTimer)
+            data.dactylScrollTimer.cancel();
+
+        x = data.dactylScrollDestX = Math.min(x, elem.scrollWidth  - elem.clientWidth);
+        y = data.dactylScrollDestY = Math.min(y, elem.scrollHeight - elem.clientHeight);
+        let [startX, startY] = [elem.scrollLeft, elem.scrollTop];
+        let n = 0;
+        (function next() {
+            if (n++ === steps) {
+                elem.scrollLeft = x;
+                elem.scrollTop  = y;
+                delete data.dactylScrollDestX;
+                delete data.dactylScrollDestY;
+            }
+            else {
+                elem.scrollLeft = startX + (x - startX) / steps * n;
+                elem.scrollTop  = startY + (y - startY) / steps * n;
+                data.dactylScrollTimer = util.timeout(next, time / steps);
+            }
+        }).call(this);
+    },
+
     /**
      * Scrolls the currently given element horizontally.
      *
@@ -1353,6 +1389,7 @@ var Buffer = Module("buffer", {
     scrollHorizontal: function scrollHorizontal(elem, unit, number) {
         let fontSize = parseInt(DOM(elem).style.fontSize);
 
+        let data = elem;
         elem = Buffer.Scrollable(elem);
         let increment;
         if (unit == "columns")
@@ -1364,8 +1401,8 @@ var Buffer = Module("buffer", {
 
         dactyl.assert(number < 0 ? elem.scrollLeft > 0 : elem.scrollLeft < elem.scrollWidth - elem.clientWidth);
 
-        let left = elem.dactylScrollDestX !== undefined ? elem.dactylScrollDestX : elem.scrollLeft;
-        elem.dactylScrollDestX = undefined;
+        let left = data.dactylScrollDestX !== undefined ? data.dactylScrollDestX : elem.scrollLeft;
+        data.dactylScrollDestX = undefined;
 
         Buffer.scrollTo(elem, left + number * increment, null, "h-" + unit);
     },
@@ -1385,6 +1422,7 @@ var Buffer = Module("buffer", {
     scrollVertical: function scrollVertical(elem, unit, number) {
         let fontSize = parseInt(DOM(elem).style.lineHeight);
 
+        let data = elem;
         elem = Buffer.Scrollable(elem);
         let increment;
         if (unit == "lines")
@@ -1396,8 +1434,8 @@ var Buffer = Module("buffer", {
 
         dactyl.assert(number < 0 ? elem.scrollTop > 0 : elem.scrollTop < elem.scrollHeight - elem.clientHeight);
 
-        let top = elem.dactylScrollDestY !== undefined ? elem.dactylScrollDestY : elem.scrollTop;
-        elem.dactylScrollDestY = undefined;
+        let top = data.dactylScrollDestY !== undefined ? data.dactylScrollDestY : elem.scrollTop;
+        data.dactylScrollDestY = undefined;
 
         Buffer.scrollTo(elem, null, top + number * increment, "v-" + unit);
     },
@@ -2234,6 +2272,28 @@ var Buffer = Module("buffer", {
                 }
             });
 
+        options.add(["scrolltime", "st"],
+            "The time, in milliseconds, in which to smooth scroll to a new position",
+            "number", 100);
+
+        options.add(["scrollsteps", "ss"],
+            "The number of steps in which to smooth scroll to a new position",
+            "number", 5,
+            {
+                PREF: "general.smoothScroll",
+
+                initValue: function () {},
+
+                getter: function getter(value) !prefs.get(this.PREF) ? 1 : value,
+
+                setter: function setter(value) {
+                    prefs.set(this.PREF, value > 1);
+                    return value > 1 ? value : this.globalValue;
+                },
+
+                validator: function (value) value > 0
+            });
+
         options.add(["usermode", "um"],
             "Show current website without styling defined by the author",
             "boolean", false,
diff --git a/common/locale/en-US/options.xml b/common/locale/en-US/options.xml
index 9fdb0554..f1a9975a 100644
--- a/common/locale/en-US/options.xml
+++ b/common/locale/en-US/options.xml
@@ -1381,6 +1381,28 @@
     </description>
 </item>
 
+<item>
+    <tags>'ss' 'scrollsteps'</tags>
+    <spec>'scrollsteps' 'ss'</spec>
+    <type>&option.scrollsteps.type;</type>
+    <default>&option.scrollsteps.default;</default>
+    <description>
+        <p>
+            The number of steps in which to smooth scroll to a new position. If
+            set to 1, smooth scrolling is not used.
+        </p>
+    </description>
+</item>
+<item>
+    <tags>'st' 'scrolltime'</tags>
+    <spec>'scrolltime' 'st'</spec>
+    <type>&option.scrolltime.type;</type>
+    <default>&option.scrolltime.default;</default>
+    <description>
+        <p>The time, in milliseconds, in which to smooth scroll to a new position.</p>
+    </description>
+    </item>
+
 <item>
     <tags>'spl' 'spelllang'</tags>
     <spec>'spelllang' 'spl'</spec>
diff --git a/common/modules/storage.jsm b/common/modules/storage.jsm
index 6bfa0ccd..d86a1d73 100644
--- a/common/modules/storage.jsm
+++ b/common/modules/storage.jsm
@@ -329,7 +329,11 @@ var File = Class("File", {
     /**
      * @property {nsIFileURL} Returns the nsIFileURL object for this file.
      */
-    get URI() services.io.newFileURI(this).QueryInterface(Ci.nsIFileURL),
+    URI: Class.Memoize(function () {
+        let uri = services.io.newFileURI(this).QueryInterface(Ci.nsIFileURL);
+        uri.QueryInterface(Ci.nsIMutable).mutable = false;
+        return uri;
+    }),
 
     /**
      * Iterates over the objects in this directory.
diff --git a/pentadactyl/NEWS b/pentadactyl/NEWS
index 3f6ecbe9..dc7697aa 100644
--- a/pentadactyl/NEWS
+++ b/pentadactyl/NEWS
@@ -73,6 +73,7 @@
     • Improved [macro-string] support, including automatic elision
       of optional elements, and array subscripts. [b4][b7]
     • Add -pentadactyl-remote command-line option. [b8]
+    • Moved the smooth-scroll plugin to the core. [b8]
     • Improvements to marks:
       - Marks are now stored as line and column ordinals rather than percentages. [b8]
       - Marks now store the marked element and ensure its visibility when followed. [b8]
@@ -218,6 +219,7 @@
       - Added 'passunknown' option. [b7]
       - Changed 'urlseparator' default value to "|". [b3]
       - Added "errorconsole", "passwords", and "venkman" dialogs to :dialog. [b2][b8]
+      - Added 'scrollsteps' and 'scrolltime' options. [b8]
       - Added 'spelllang' option. [b8]
       - Make 'showmode' a [stringlist] option. [b7]
       - Added 'wildanchor' option. [b2]