TL;DR
Brave says it has substantially reduced the memory footprint of its Rust-written adblocking engine, claiming roughly 45 MB of default savings and about a 75% reduction since reengineering began. The company credits a shift to a zero-copy binary format using FlatBuffers and several other memory-optimization techniques; independent measurements show similar but variable reductions.
What happened
Brave Software overhauled the Rust-based component that handles ad and tracker blocking in its browser, focusing on lowering memory consumption and improving efficiency. Engineers migrated the roughly 100,000 default adblock filters out of standard heap-allocated Rust structures into a specialized zero-copy binary format using FlatBuffers, and added other optimizations such as stack-allocated vectors, tokenized regex patterns, shared resources among adblock engines, and compact storage. Brave reports about a 75% reduction in adblock-related memory use since the rework began, which it quantifies as roughly 45 MB saved by default across Android, iOS and desktop. Version comparisons cited by the company place the adblock engine footprint at about 104 MB in version 1.85.118, down from 162 MB in version 1.79.118 (May 2025). Independent checks by The Register produced somewhat different per-run numbers and observed a GPU-process memory increase that Brave says is unrelated to the adblock changes.
Why it matters
- Lower memory usage can improve battery life on mobile devices and leave more RAM available for other apps, helping multitasking.
- Moving to a zero-copy format reduces runtime parsing and heap allocation overhead, which can speed filter matching and page loading.
- Using Rust for this component reduces exposure to whole classes of memory-safety bugs compared with unsafe languages.
- The work illustrates a broader industry trend of integrating Rust and modern serialization techniques into browser stacks.
Key facts
- Brave reports approximately 75% reduction in adblock-engine memory consumption since reengineering began.
- The company cites roughly 45 MB of default memory savings across Android, iOS and desktop platforms.
- Brave lists the adblock-engine footprint at about 104 MB in version 1.85.118, versus 162 MB in version 1.79.118 (May 2025).
- Earlier intermediate reductions recorded by Brave: June 2025 — 150 MB to 121 MB; October 2025 — 119 MB to 108 MB.
- The refactor moved ~100,000 default adblock filters from heap-allocated Rust data structures (Vecs, HashMaps, structs) into a specialized zero-copy binary using FlatBuffers.
- Other engineering changes include stack-allocated vectors, tokenized common regex patterns, resource sharing across adblock engines, and optimized memory storage.
- An independent check by The Register on macOS observed task-manager footprints of 121 MB after reinstall and 106 MB after disabling Brave's Leo AI assistant; Brave contests single-run comparisons.
- A screenshot cited in reporting showed a GPU process memory increase between versions (52.2 MB to 81.9 MB); Brave said that change is unrelated to the adblock-engine improvements.
What to watch next
- Independent, repeatable benchmarks across platforms to validate Brave's averaged memory-savings claims.
- Behavior of GPU-process memory in broader tests to confirm whether changes are isolated or systemic.
- Timing and details for the Brave Origin variant and its exclusion of features such as sponsored images, Rewards, Wallet, VPN, Leo, and telemetry — not confirmed in the source.
Quick glossary
- FlatBuffers: A cross-platform serialization library that enables accessing structured data without unpacking or parsing it first, reducing runtime overhead.
- Zero-copy: A data-handling approach where consumers read data directly from a stored binary representation without making intermediate copies, lowering memory and CPU costs.
- Rust: A systems programming language designed to provide performance comparable to C/C++ while preventing common memory-safety bugs through its ownership and borrowing rules.
- Adblock filter: A rule or pattern used by adblocking software to identify and block requests, resources, or page elements associated with ads and trackers.
- Heap allocation: Runtime allocation of memory from a program’s heap area, typically used for dynamically sized data structures and frequently a source of performance and fragmentation concerns.
Reader FAQ
How much memory did Brave claim to save?
Brave says its rework yields roughly 45 MB saved by default across platforms and reports about a 75% reduction in adblock-related memory use since the project began.
Will this make web pages load faster or save battery?
Brave states that blocking ads and trackers reduces downloaded resources and that the memory improvements have led to better performance and battery life on mobile devices; independent measurements were not provided in the source.
Does this change make Brave more secure?
Brave argues that using Rust for the adblock engine improves safety by eliminating whole classes of memory-safety bugs; the source attributes this as a security benefit.
When will the Brave Origin paid variant ship?
Not confirmed in the source.
APPLICATIONS 2 Brave refurbishes Rust adblocking engine for reduced memory footprint Have your privacy cake and consume the web too Thomas Claburn Tue 6 Jan 2026 // 22:24 UTC Brave Software has reworked its…
Sources
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