Add simple diff+patch perf test

perf/diff.js

@@ -0,0 +1,51 @@
+var jiff = require('../jiff');
+var json = require('gent/generator/json');
+
+
+var n = 4;
+var o = json.object(8);
+var a = makeArray(o, 1, 1000);
+
+test(a);
+
+var start = Date.now();
+for(var i=0; i<n; ++i) {
+	test(a);
+}
+console.log((Date.now() - start) / n);
+
+function test(array) {
+	return testPatch(testDiff(array), array);
+}
+
+function testDiff(array) {
+	return jiff.diff(array, modify(array), byId);
+}
+
+function testPatch (patch, array) {
+	return jiff.patch(patch, array);
+}
+
+function modify(array) {
+	var a2 = array.slice();
+	a2.splice(Math.floor(a2.length/2), Math.min(10, a2.length));
+	return a2.concat(makeArray(o, array.length+1, 2));
+}
+
+function makeArray(o, id, n) {
+	var a = new Array(n);
+	for(var i=0; i<n; ++i) {
+		a[i] = getObject(o, id++);
+	}
+	return a;
+}
+
+function getObject(o, id) {
+	var x = o.next().value;
+	x.id = id;
+	return JSON.parse(JSON.stringify(x));
+}
+
+function byId(x) {
+	return x.id || JSON.stringify(x);
+}