Zcash is brewing the NU 8 upgrade: 4x block capacity expansion, privacy transactions sprinting toward 200 per second, and post-quantum solutions advancing in parallel.

Zcash developer ValarDragon has proposed the NU 8 network upgrade, targeting a late-January 2027 activation window, centered on a new Tachyon shielded pool, an increase in the maximum block size from 2MB to 8MB (a 4x expansion), and the introduction of quantum-resistant signature opcodes. The proposal estimates shielded transaction throughput could reach 200 TPS, addressing a long-standing performance bottleneck for privacy-focused chains, while the Tachyon pool would use ML-KEM encapsulation for post-quantum privacy and transparent addresses would gain 128-bit and 192-bit SPHINCS (SLH-DSA) signature support. Core engineer str4d has pushed back on the 8MB block size, warning that out-of-band communication and private information retrieval specifications for light wallets are not yet finalized and that the larger blocks would increase sync burdens on mobile clients. The proposal also includes the ZIP 248 transaction format to reduce metadata fingerprinting, removal of mandatory Consensus Branch ID changes per upgrade (with str4d cautioning that a replay-protection replacement must first be established), and a phased deprecation of the Sapling pool via a deposit cutoff rather than a hard freeze. The network sustainability mechanism redistribution point would be shifted to around Zcash's seventh halving, delaying tail issuance pressure by four to eight years. The proposal remains in public technical discussion on the official forum, with PIR specifications and replay-protection alternatives needing review before code consensus, specification finalization, and a community NU 8 governance vote.