diff --git a/ext/mixed/js/timer.js b/ext/mixed/js/timer.js
new file mode 100644
index 00000000..87ab62a7
--- /dev/null
+++ b/ext/mixed/js/timer.js
@@ -0,0 +1,96 @@
+/*
+ * Copyright (C) 2019  Alex Yatskov <alex@foosoft.net>
+ * Author: Alex Yatskov <alex@foosoft.net>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+class Timer {
+    constructor(name) {
+        this.samples = [];
+        this.parent = null;
+
+        this.sample(name);
+        const current = Timer._current;
+        if (current !== null) {
+            current.samples[current.samples.length - 1].children.push(this);
+            this.parent = current;
+        }
+        Timer._current = this;
+    }
+
+    sample(name) {
+        const time = window.performance.now();
+        this.samples.push({
+            name,
+            time,
+            children: []
+        });
+    }
+
+    complete(skip) {
+        this.sample('complete');
+
+        Timer._current = this.parent;
+        if (this.parent === null) {
+            if (!skip) {
+                console.log(this.toString());
+            }
+        } else {
+            if (skip) {
+                const sample = this.parent.samples[this.parent.samples.length - 1];
+                sample.children.splice(sample.children.length - 1, 1);
+            }
+        }
+    }
+
+    duration(sampleIndex) {
+        const sampleIndexIsValid = (typeof sampleIndex === 'number');
+        const startIndex = (sampleIndexIsValid ? sampleIndex : 0);
+        const endIndex = (sampleIndexIsValid ? sampleIndex + 1 : this.times.length - 1);
+        return (this.times[endIndex].time - this.times[startIndex].time);
+    }
+
+    toString() {
+        const indent = '  ';
+        const name = this.samples[0].name;
+        const duration = this.samples[this.samples.length - 1].time - this.samples[0].time;
+        const extensionName = chrome.runtime.getManifest().name;
+        return `${name} took ${duration.toFixed(8)}ms  [${extensionName}]` + Timer._indentString(this.getSampleString(), indent);
+    }
+
+    getSampleString() {
+        const indent = '  ';
+        const duration = this.samples[this.samples.length - 1].time - this.samples[0].time;
+        let message = '';
+
+        for (let i = 0, ii = this.samples.length - 1; i < ii; ++i) {
+            const sample = this.samples[i];
+            const sampleDuration = this.samples[i + 1].time - sample.time;
+            message += `\nSample[${i}] took ${sampleDuration.toFixed(8)}ms (${((sampleDuration / duration) * 100.0).toFixed(1)}%)  [${sample.name}]`;
+            for (const child of sample.children) {
+                message += Timer._indentString(child.getSampleString(), indent);
+            }
+        }
+
+        return message;
+    }
+
+    static _indentString(message, indent) {
+        return message.replace(/\n/g, `\n${indent}`);
+    }
+}
+
+Timer._current = null;