March Bitcoin Technology Update: Mempool Progress and BIP-360
Bitcoin BTC +0.00% ’s protocol layer saw meaningful progress in March 2026, with Bitcoin Core 29.1 shipping lower default fee thresholds, cluster mempool development advancing through multiple pull requests, and BIP-360 formalizing a draft proposal for quantum-resistant outputs. None of these changes are fully deployed yet, but together they mark a notable month for Bitcoin infrastructure work.
What March’s Bitcoin Mempool Upgrades Actually Changed
Bitcoin Core 29.1, released in March, lowered the default minimum relay feerate and incremental relay feerate to 100 satoshis per kvB and dropped the blockmintxfee to 1 satoshi per kvB. These are policy defaults, not consensus changes, meaning node operators can still override them.
The practical effect is that transactions paying very low fees now propagate more easily across the network. For users, this reduces the cost floor during calm mempool periods, which is where Bitcoin sat at the end of March, with Mempool.space recommending just JST +0.00% 4 sat/vB for fastest confirmation and 3 sat/vB for half-hour and one-hour targets.
These low fees reflect a relatively uncongested network. Bitcoin traded at $68,877 with a market cap near $1.378 trillion at the time of writing, in a month where Bitcoin logged its first green month after five months of losses.
Cluster Mempool Work Continues
Separate from the shipped 29.1 release, Bitcoin’s broader mempool redesign, known as the cluster mempool project, continued advancing. Bitcoin Optech’s tracking page lists ongoing 2026 work including Bitcoin Core pull requests #34616 and #32545.
Cluster mempool aims to restructure how Bitcoin nodes evaluate and prioritize unconfirmed transactions. The redesign is still in progress, not yet merged into a stable STABLE +0.00% release. It is important to distinguish this from the 29.1 fee-policy changes, which are live now.
Why BIP-360 Matters in Bitcoin’s Quantum-Resistance Discussion
BIP 360 is a draft Bitcoin Improvement Proposal introducing a new output type called Pay-to-Merkle-Root, or P2MR. The proposal keeps Taproot-like script-tree functionality while removing the key-path spend, which the spec explicitly describes as quantum vulnerable.
The design rationale is conservative. P2MR does not attempt to implement full post-quantum cryptography in Bitcoin. Instead, it eliminates the specific spending path that would be exploitable by a sufficiently powerful quantum computer, one that could derive a private key from an exposed public key.
“The key spend is not quantum-safe because it exposes the public key.”
— Ethan Heilman, via Decrypt
BIP-360 is a draft, not an activated soft fork. It has not reached rough consensus among Bitcoin developers, and no activation timeline exists. The BIP process requires extensive review, testing, and community agreement before any consensus-layer change can be deployed, the same governance path that Taproot itself followed over several years.
Some competitor coverage has centered on the quantum-risk debate, but the verifiable takeaway is narrower: a specific proposal now exists in draft form, addressing a specific vulnerability, through a specific mechanism. Whether the broader Bitcoin community will prioritize this work depends on how the threat timeline is assessed, a question on which analysts remain split on Bitcoin’s near-term trajectory for different reasons entirely.
What Bitcoin Users and Developers Should Watch Next
For mempool improvements, the signals to monitor are straightforward. Future Bitcoin Core releases will indicate whether cluster mempool components move from open pull requests to merged code. Optech’s topic page remains the best public tracker for this work.
For BIP-360, real progress beyond draft status would include formal review sessions, reference implementations, and eventually a testnet deployment. None of these milestones have been announced. Users should treat P2MR as a proposal-stage idea, not a live network change or an imminent upgrade.
The current fee environment, with recommended rates at 3 to 4 sat/vB, suggests the network is not under transaction-volume pressure. This calm period is precisely when protocol-level work tends to advance most effectively, without the urgency of congestion forcing short-term fixes.
March also saw $52 million in crypto hacks across 20 incidents, a reminder that security improvements at the protocol layer, whether mempool policy or quantum-resistance proposals, exist alongside ongoing application-layer risks. The two operate on very different timescales and threat models.
Disclaimer: This article is for informational purposes only and does not constitute financial or investment advice. Cryptocurrency and digital asset markets carry significant risk. Always do your own research before making decisions.
