Bitcoin Core V31 Lands With Privacy And Performance Overhaul

Cluster Mempool and Private Broadcasting

Bitcoin Core v31 has arrived following the v31.0rc4 testnet release on April 11, marking what developers describe as the most significant architectural change to $BTC's transaction handling in years. The headline feature is a redesigned "cluster mempool" that organises unconfirmed transactions into bounded groups — capped at 64 transactions or 101 kB in virtual size — replacing the topology-limited structure Bitcoin nodes have relied on since the network's earliest days.

The practical impact goes well beyond plumbing. The new design directly affects how miners build blocks, how wallets estimate fees, and how complex transaction packages — think batched payments or Lightning channel closures — are prioritised. Under the old system, related transactions could trip over descendant limits; under cluster mempool, the node handles fee-rate sorting internally, removing the need for wallets to work around topology constraints.

On the privacy front, v31 introduces a -privatebroadcast flag that routes transaction broadcasts exclusively through Tor or I2P. When enabled, the originator's IP address and geolocation are never exposed to recipients, and separate connections are used for each broadcast, making it impossible to link two otherwise unrelated transactions by network identity. That matters because chain analysis firms have long run thousands of listening nodes to catch the moment a transaction first appears on the clearnet — correlating the originating IP with a wallet address. V31 closes that gap at the protocol level.

BIP-361 Brings Quantum Migration Into the Same Cycle

The release coincides with growing momentum around BIP-361, formally titled "Post Quantum Migration and Legacy Signature Sunset," which was assigned in February 2026 and co-authored by Casa CTO Jameson Lopp and five others. The proposal, currently in informational draft status, outlines a three-phase plan to retire legacy cryptographic signature paths before quantum computers become a credible threat.

The stakes are material. Estimates cited in the proposal suggest more than 34% of all $BTC in circulation sits in addresses where public keys are already exposed on-chain — vulnerable to a sufficiently powerful quantum machine running Shor's algorithm. Phase A of BIP-361, expected roughly three years after activation, would block new funds from being sent to legacy address types. Phase B, kicking in around five years post-activation, would invalidate all legacy signatures at the consensus layer — any bitcoin that has not migrated by that point would be effectively frozen. A potential Phase C proposes a zero-knowledge proof recovery mechanism for holders who miss the deadline but retain their seed phrase.

Taken together, v31 and BIP-361 place $BTC's base layer on a dual track: tightening network-level privacy in the near term while laying the groundwork for a post-quantum transition over a longer horizon. Full production release of Bitcoin Core v31 is expected in the second half of 2026, though the project does not commit to fixed dates.

Sources:
Bitcoin Core 31.0 Official Release Notes
Bitcoin.com News — BIP-361 Quantum Migration Proposal
CoinTelegraph — Bitcoin BIP-361 Targets Quantum Security Threat

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