diff --git a/.gitignore b/.gitignore
index 05b994c..9434000 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,3 +9,5 @@ configure
 install-sh
 missing
 *.tmp
+*_timestamp
+*.cache
diff --git a/src/SplitJob.class b/src/SplitJob.class
new file mode 100644
index 0000000..10c467d
Binary files /dev/null and b/src/SplitJob.class differ
diff --git a/src/SplitJob.java b/src/SplitJob.java
new file mode 100644
index 0000000..8498be6
--- /dev/null
+++ b/src/SplitJob.java
@@ -0,0 +1,54 @@
+
+import java.io.*;
+
+import static java.lang.ProcessBuilder.Redirect;
+
+public class SplitJob {
+
+	private static final BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
+
+
+	public static void main(String[] args) {
+
+		final Runtime runtime = Runtime.getRuntime();
+		int numThreads = runtime.availableProcessors();
+		Process[] procs = new Process[numThreads];
+
+		try {
+		
+			ProcessBuilder builder = new ProcessBuilder(args);
+			builder.redirectError(Redirect.INHERIT);
+		
+			for (int i = 0; i < numThreads; i++) {
+				procs[i] = builder.start();
+			}
+		
+			for (int i = 0; ; i = (i + 1) % numThreads) {
+	
+				String s = in.readLine();
+
+				if (s == null)
+					break;
+
+				byte[] data = (s + '\n').getBytes();
+				procs[i].getOutputStream().write(data, 0, data.length);
+				procs[i].getOutputStream().flush();
+			}
+		
+			for (Process proc : procs) {
+			
+				proc.getOutputStream().close();
+				int exitCode = proc.waitFor();
+				
+				if (exitCode != 0) {
+					System.err.printf("[Error] %s stopped with exit code: %d\n", args[0], exitCode);
+					System.exit(2);
+				}
+			}
+			
+		} catch (Exception e) {
+			System.err.printf("[Error] %s: %s\n", e.getClass().getName(), e.getMessage());
+			System.exit(1);
+		}
+	}
+}
diff --git a/src/render_icons.sh b/src/render_icons.sh
old mode 100644
new mode 100755
index 9152e8d..bbbe079
--- a/src/render_icons.sh
+++ b/src/render_icons.sh
@@ -1,7 +1,6 @@
 #!/bin/bash
 
 INKSCAPE="/usr/bin/inkscape"
-OPTIPNG="/usr/bin/optipng"
 
 pushd `dirname $0` > /dev/null
 DIR="$( cd "$(dirname "$0")" ; pwd -P )"
@@ -9,62 +8,116 @@ popd > /dev/null
 
 cd ${DIR}
 
-THEMEDIR=../Arc
-
-mkdir -p $THEMEDIR
+TYPES=(actions apps categories devices emblems mimetypes places status)
+SIZES=(16 22 24 32 48 64 96 128)
 
-for CONTEXT in actions apps categories devices emblems mimetypes places status
-do
+THEMEDIR=../Arc
 
-    mkdir -p $THEMEDIR/$CONTEXT
-    mkdir -p $THEMEDIR/$CONTEXT
+# Set up all the folders in the theme directory.
+mkdir -p $THEMEDIR/{actions,apps,categories,devices,emblems,mimetypes,places,status}/{16,22,24,32,48,64,96,128}{,@2x}
 
-    cp -r $CONTEXT/symbolic $THEMEDIR/$CONTEXT
+cp -u index.theme $THEMEDIR/index.theme
 
-    for SIZE in 16 22 24 32 48 64 96 128
+for CONTEXT in ${TYPES[@]}
+do
+    for SIZE in ${SIZES[@]}
     do
-        $INKSCAPE -S $CONTEXT.svg | grep -E "_$SIZE" | sed 's/\,.*$//' > index.tmp
-
-        mkdir -p $THEMEDIR/$CONTEXT/$SIZE
-        mkdir -p $THEMEDIR/$CONTEXT/$SIZE@2x
-
-        cp -r $CONTEXT/symlinks/* $THEMEDIR/$CONTEXT/$SIZE
-        cp -r $CONTEXT/symlinks/* $THEMEDIR/$CONTEXT/$SIZE@2x
-
-        for OBJECT_ID in `cat index.tmp`
-        do
-
-            ICON_NAME=$(sed "s/\_$SIZE.*$//" <<< $OBJECT_ID)
-
-            if [ -f $THEMEDIR/$CONTEXT/$SIZE/$ICON_NAME.png ]; then
-                echo $THEMEDIR/$CONTEXT/$SIZE/$ICON_NAME.png exists.
-            else
-                echo
-                echo Rendering $THEMEDIR/$CONTEXT/$SIZE/$ICON_NAME.png
-                $INKSCAPE --export-id=$OBJECT_ID \
-                          --export-id-only \
-                          --export-png=$THEMEDIR/$CONTEXT/$SIZE/$ICON_NAME.png $CONTEXT.svg >/dev/null \
-                && $OPTIPNG -o7 --quiet $ASSETS_DIR/$i.png 
-            fi
-            if [ -f $THEMEDIR/$CONTEXT/$SIZE@2x/$ICON_NAME.png ]; then
-                echo $THEMEDIR/$CONTEXT/$SIZE@2x/$ICON_NAME.png exists.
-            else
-                echo
-                echo Rendering $THEMEDIR/$CONTEXT/$SIZE@2x/$ICON_NAME.png
-                $INKSCAPE --export-id=$OBJECT_ID \
-                          --export-dpi=180 \
-                          --export-id-only \
-                          --export-png=$THEMEDIR/$CONTEXT/$SIZE@2x/$ICON_NAME.png $CONTEXT.svg >/dev/null \
-                && $OPTIPNG -o7 --quiet $ASSETS_DIR/$i@2.png 
-            fi
-        done
+        cp -ru $CONTEXT/symlinks/* $THEMEDIR/$CONTEXT/$SIZE
+        cp -ru $CONTEXT/symlinks/* $THEMEDIR/$CONTEXT/$SIZE@2x
+        cp -ru $CONTEXT/symbolic $THEMEDIR/$CONTEXT
     done
 done
 
-rm index.tmp
-cp index.theme $THEMEDIR/index.theme
 rm -rf $THEMEDIR/actions/{32,32@2x,48,48@2x,64,64@2x,96,96@2x,128,128@2x} # derp
 
 # TODO
-cp -r animations $THEMEDIR/.
-cp -r panel $THEMEDIR/.
+cp -ru animations $THEMEDIR/.
+cp -ru panel $THEMEDIR/.
+
+# Ensure cache folder exists
+mkdir .cache
+
+# Takes in an svg-file and an object-id and formats it
+# to an inkscape export shell command that inkscape can
+# then execute.
+formatInkscapeCmd() {
+
+    local CONTEXT=$1
+    local OBJECT_ID=$2
+    local SIZE=$(sed -r 's/.*\_([0-9]+).*$/\1/' <<< $OBJECT_ID)
+
+    local ICON_NAME=$(sed "s/\_$SIZE.*$//" <<< $OBJECT_ID)
+
+        echo \
+            "--export-id=$OBJECT_ID" \
+            "--export-id-only" \
+            "--export-png=$THEMEDIR/$CONTEXT/$SIZE/$ICON_NAME.png $CONTEXT.svg"
+    
+        echo \
+            "--export-id=$OBJECT_ID" \
+            "--export-dpi=180" \
+            "--export-id-only" \
+            "--export-png=$THEMEDIR/$CONTEXT/$SIZE@2x/$ICON_NAME.png $CONTEXT.svg"
+}
+
+# Generates inkscape export commands for the given
+# svg-file that can be piped to inkscape.
+genInkscapeCmds() {
+
+    local CONTEXT=$1
+
+    for SIZE in ${SIZES[@]}
+    do
+        for OBJECT_ID in `cat <($INKSCAPE -S $CONTEXT.svg | grep -E "_$SIZE" | sed 's/\,.*$//')`
+        do
+            echo $OBJECT_ID >> .cache/$CONTEXT.cache.tmp
+            formatInkscapeCmd $CONTEXT $OBJECT_ID
+        done
+    done
+    mv .cache/$CONTEXT.cache.tmp .cache/$CONTEXT.cache
+}
+
+# Generates inkscape export commands that matches
+# the provided regex pattern.
+genInkscapeCmdsFiltered() {
+    
+    local CONTEXT=$1
+    local REGEX=$2
+    
+    while read -r OBJECT_ID
+    do
+        echo "Match: $OBJECT_ID" >&2
+        formatInkscapeCmd $CONTEXT $OBJECT_ID
+    done < <(grep -E $REGEX .cache/$CONTEXT.cache)
+}
+
+if [[ ! -z $1 ]]
+then
+    echo "Rendering objects with IDs matching regex"
+    for CONTEXT in ${TYPES[@]}
+    do
+        if [[ -f .cache/$CONTEXT.cache ]] || { [[ ! -f .cache/$CONTEXT.cache ]] && ($INKSCAPE -S $CONTEXT.svg | grep -E "_[0-9]+" | sed 's/\,.*$//' > .cache/$CONTEXT.cache.tmp); }
+        then
+            mv .cache/$CONTEXT.cache.tmp .cache/$CONTEXT.cache 2> /dev/null
+            genInkscapeCmdsFiltered $CONTEXT $1 | java SplitJob $INKSCAPE --shell
+        else
+            echo "Failed creating creating object-ID cache for $CONTEXT.svg"
+        fi
+    done
+else
+    for CONTEXT in ${TYPES[@]}
+    do
+        # Only render out the icons if the svg-file has been modified
+        # since we finished rendering it out last.
+        if [[ $CONTEXT.svg -nt .cache/${CONTEXT}_timestamp ]]
+        then
+            echo "Rendering icons from $CONTEXT.svg"
+            genInkscapeCmds $CONTEXT | java SplitJob $INKSCAPE --shell && touch .cache/${CONTEXT}_timestamp
+        else
+            echo "No changes to $CONTEXT.svg, skipping..."
+        fi
+    done
+fi
+    
+# Remove all empty directories from the theme folder.
+find $THEMEDIR -type d -empty -delete