diff -r fa42b3d8cbbc -r a48961ff3e6b vm/src/main/java/org/apidesign/vm4brwsr/Zips.java
--- a/vm/src/main/java/org/apidesign/vm4brwsr/Zips.java	Thu Feb 07 13:41:56 2013 +0100
+++ b/vm/src/main/java/org/apidesign/vm4brwsr/Zips.java	Sun Feb 10 12:14:40 2013 +0100
@@ -19,17 +19,25 @@
 
 import java.io.ByteArrayInputStream;
 import java.io.IOException;
+import java.io.InputStream;
 import java.net.URL;
-import java.util.zip.ZipEntry;
-import java.util.zip.ZipInputStream;
 import org.apidesign.bck2brwsr.core.JavaScriptBody;
+import org.apidesign.bck2brwsr.emul.zip.FastJar;
 
 /** Conversion from classpath to load function.
  *
  * @author Jaroslav Tulach <jtulach@netbeans.org>
  */
 final class Zips {
-    private Zips() {
+    private final FastJar fj;
+
+    private Zips(String path, byte[] zipData) throws IOException {
+        long bef = currentTimeMillis();
+        fj = new FastJar(zipData);
+        for (FastJar.Entry e : fj.list()) {
+            putRes(e.name, e);
+        }
+        log("Iterating thru " + path + " took " + (currentTimeMillis() - bef) + "ms");
     }
     
     public static void init() {
@@ -64,38 +72,32 @@
         }
         return null;
     }
+    
+    @JavaScriptBody(args = { "msg" }, body = "console.log(msg.toString());")
+    private static native void log(String msg);
+
+    private byte[] findRes(String res) throws IOException {
+        Object arr = findResImpl(res);
+        if (arr instanceof FastJar.Entry) {
+            long bef = currentTimeMillis();
+            InputStream zip = fj.getInputStream((FastJar.Entry)arr);
+            arr = readFully(new byte[512], zip);
+            putRes(res, arr);
+            log("Reading " + res + " took " + (currentTimeMillis() - bef) + "ms");
+        }
+        return (byte[]) arr;
+    }
 
     @JavaScriptBody(args = { "res" }, body = "var r = this[res]; return r ? r : null;")
-    private native byte[] findRes(String res);
+    private native Object findResImpl(String res);
 
     @JavaScriptBody(args = { "res", "arr" }, body = "this[res] = arr;")
-    private native void putRes(String res, byte[] arr);
+    private native void putRes(String res, Object arr);
     
     private static Zips toZip(String path) throws IOException {
         URL u = new URL(path);
-        ZipInputStream zip = new ZipInputStream(u.openStream());
-        Zips z = new Zips();
-        for (;;) {
-            ZipEntry entry = zip.getNextEntry();
-            if (entry == null) {
-                break;
-            }
-            byte[] arr = new byte[4096];
-            int offset = 0;
-            for (;;) {
-                int len = zip.read(arr, offset, arr.length - offset);
-                if (len == -1) {
-                    break;
-                }
-                offset += len;
-                if (offset == arr.length) {
-                    enlargeArray(arr, arr.length + 4096);
-                }
-            }
-            sliceArray(arr, offset);
-            z.putRes(entry.getName(), arr);
-        }
-        return z;
+        byte[] zipData = (byte[]) u.getContent(new Class[] { byte[].class });
+        return new Zips(path, zipData);
     }
 
     private static String processClassPathAttr(final byte[] man, String url, Object[] classpath) throws IOException {
@@ -132,6 +134,28 @@
 
     @JavaScriptBody(args = { "arr", "len" }, body = "arr.splice(len, arr.length - len);")
     private static native void sliceArray(byte[] arr, int len);
+
+    private static Object readFully(byte[] arr, InputStream zip) throws IOException {
+        int offset = 0;
+        for (;;) {
+            int len = zip.read(arr, offset, arr.length - offset);
+            if (len == -1) {
+                break;
+            }
+            offset += len;
+            if (offset == arr.length) {
+                enlargeArray(arr, arr.length + 4096);
+            }
+        }
+        sliceArray(arr, offset);
+        return arr;
+    }
+
+    private static long currentTimeMillis() {
+        return (long)m();
+    }
+    @JavaScriptBody(args = {  }, body = "return window.performance.now();")
+    private static native double m();
     
     
 }