January 5, 2026
Memory wars: 45MB edition
Brave overhauled its Rust adblock engine with FlatBuffers, cutting memory 75%
Brave slashes memory 75% to save battery — commenters ask if 45MB even matters
TLDR: Brave rebuilt its ad blocker to pack data tightly, cutting memory use by about 75% (~45MB) for smoother browsing and better battery. Comments split between “45MB is nothing,” “is it per tab?!,” open‑source praise, and a few tempted to switch—proof that even small savings spark big browser debates.
Brave says its built‑in ad blocker just went on a 75% memory diet, shaving roughly 45MB on phones and desktops by squeezing its rulebook into a tighter format. Translation for non‑devs: they packed the data so the browser can read it fast without unpacking bulky boxes. The update is live in v1.85, with more polish in v1.86, and Brave’s flex is that it’s built‑in (not an extension), so it dodges Chrome’s controversial extension limits and stays snappy.
But the comment section? Spicy. One camp shrugs: “45MB, in 2026? Meh.” Another fires back with panic‑eyes: “Wait, is that 45MB per tab?” If every tab is its own process, the savings could multiply — or not — cue speculation and side‑eyes. Optimists cheer the old‑school vibe of shipping lean code again, while others gush over the open‑source angle: Brave uses components from Mozilla’s Servo project and publishes its own engine for anyone to reuse. Meanwhile, a curveball: someone discovers Brave’s vertical tabs and suddenly considers ditching Firefox. The crowd erupts with classic memes: “45MB is one Chrome tab,” “that’s three cat photos,” and “every byte counts on budget phones.”
Under the hood, Brave also claims faster rule‑matching and shared resources to save even more memory. But the real headline is the culture clash: is 45MB a rounding error, or a legit win for battery life and low‑end devices? The jury (and the tabs) are still open.
Key Points
- •Brave refactored its Rust-based adblock engine to use FlatBuffers, reducing memory usage by about 75% (~45 MB) across platforms.
- •The change moves ~100,000 default filters from heap-allocated Rust structures to a zero-copy binary format.
- •Additional optimizations include 19% fewer allocations and ~15% faster build times via stack-allocated vectors.
- •Filter matching performance improved by 13% through tokenizing common regex patterns; shared resources save ~2 MB on desktop.
- •Enhancements are live in Brave v1.85, with more in v1.86, and Brave’s native adblocking remains unaffected by Manifest V3.