A highly structured and comprehensive performance guide for Firefox/Zen Browser users seeking peak responsiveness, efficiency and memory management optimized for 4GB, 8GB and 16GB RAM systems.
🧪 Tested Performance Improvement: Speedometer 3.1 benchmark on 2016 ASUS laptop (i5-6300HQ, 8GB RAM, GTX 960M, 70 Mbps) improved from 6.90 → 10.10 (+47%) with these optimizations.
I fell in love with the concept of Arc and Zen, but after thoroughly testing almost every browser available, I ultimately chose Vivaldi - it’s simply better in almost every way.
I’m not trying to make a browser tier list, but here’s what I’ve tested: Chrome, Edge, Arc, Zen, Firefox, Floorp, Librefox, Comet, Brave and a handful of others ones. While some browsers (like Brave) do offer unique features and unique bloats, Vivaldi stands out as the best overall balance for me. For reference, Edge was the only browser where I scored ~14 on DOM performance, while Vivaldi matched Chrome’s results, Arc was the slowest chromium based browser.
On the other hand, any unoptimized Firefox gave me a score of ~7 in DOM, ~85 in WebAssembly/JavaScript, and ~500 in 3D (with 2 GPU compatibility issues). After optimization, those numbers improved to ~10, ~105, and ~650 respectively.
Meanwhile, Vivaldi consistently delivers ~13 DOM, ~166 WebAssembly/JavaScript, and ~1200 in 3D. Even with lots of custom CSS to mimic the look of Zen/Arc, strong privacy settings, proper site isolation, and good security - it still uses less RAM and offers broader compatibility and stability.
On the Chrome side, experimental builds are being compiled with modern CPUs in mind, dropping compatibility for pre-2011 processors in exchange for up to 30% more performance. These builds take advantage of optimizations like SSE4.2, AVX, AES, CFLAGS/LDFLAGS, thinLTO, import_instr_limit, LLVM LOOP, -mllvm flags, PGO, and other compiler tweaks.
Google is also pushing forward with a new UI and Skia Graphite (Metal, Vulkan, WebGPU) paired with GPU rasterization. You can already test it, my MotionMark score hit an impressive 2200, though it’s still unstable in practice. GPU rasterization alone, however, runs fine: pages load with both CPU and GPU working in tandem.
So, here is my sloppy custom CSS for a very compact Zen, with gradient and mica being disabled on this screenshot. Check out the Zen wiki if you want to install it, but I will not update it anymore.
Enjoy.