Safe But Slow? Quantum-Safe Security Could Slow High-Speed Blockchains

Insider Brief

• Efforts to make blockchains quantum-resistant could significantly slow transaction speeds, forcing networks like Solana to balance security with performance.
• Testing of quantum-safe cryptographic signatures showed up to 40× larger data sizes and roughly a 90% reduction in processing speed, undermining high-throughput advantages.
• The findings highlight a broader industry challenge, as all major crypto networks may face similar trade-offs between scalability, speed, and long-term security.
• Image: geralt on Pixabay

Solana’s push toward quantum-resistant security could sharply reduce its transaction speeds, highlighting a growing trade-off between future-proofing crypto networks and maintaining performance.

Solana has built its reputation on speed, processing transactions far faster than most rivals, enabling it to support large volumes of decentralized finance activity, including trading, lending, and payments. According to data cited by crypto news site AMBCrypto, the network handles more than 1,000 transactions per second, compared with roughly 26 on Ethereum.

That advantage has translated into scale. Solana has processed tens of billions more transactions than Ethereum, and its stablecoin ecosystem has expanded as users move beyond dollar-backed assets into alternatives such as euro- and real-denominated tokens. The growth reflects a broader effort to diversify and deepen liquidity across its financial applications.

But recent testing suggests that the features enabling that growth may be difficult to preserve as the industry prepares for quantum computing. For context, quantum computers could undermine cryptocurrencies by solving the mathematical problems that secure blockchain transactions far faster than today’s computers, potentially exposing wallets and enabling unauthorized transfers.

Quantum Security Comes at a Cost

Solana is working with Project Eleven to test quantum-safe cryptographic signatures. These are new methods designed to protect blockchains from future quantum computers, which could theoretically break today’s encryption systems.

The solution to replace existing signatures with quantum-resistant alternatives, at least according to very early results, present significant trade-offs.

According to AMBCrypto, the new signatures are up to 40 times larger than current ones. Larger signatures require more data to be processed and transmitted across the network. In testing, this translated into a roughly 90% reduction in transaction speed.

In practical terms, a network optimized for speed begins to behave more like a slower, more congested system.

Speed vs. Security

The findings put Solana in a difficult position. Its competitive advantage has long depended on high throughput and fast confirmation times — features that attract developers building high-frequency financial applications.

A sharp slowdown could undermine that edge, particularly as Ethereum continues to improve its own scalability through upgrades and secondary networks.

AMBCrypto reports that the slowdown raises questions about whether Solana can maintain its position in decentralized finance if performance drops significantly. Slower transaction times can increase costs, reduce liquidity efficiency, and make certain trading strategies less viable.

At the same time, ignoring quantum risk carries its own consequences. While practical quantum attacks are not yet feasible and although the timeline is uncertain, based on recent research advances, that timeline is shrinking. Networks that delay adopting quantum-safe measures could face security risks later, especially for long-lived assets and stored data.

The issue could extends beyond Solana because all major blockchains rely on similar cryptographic systems and will likely face comparable trade-offs as they transition to quantum-resistant methods.

Experts identify the key structural challenge is that quantum-safe algorithms tend to use larger keys and signatures, increasing computational and bandwidth demands. That can slow networks or require significant redesigns of how data is handled and verified.

Developers across the industry are now exploring ways to minimize these impacts. Potential approaches include hybrid systems that combine current and quantum-safe methods, as well as optimizations to reduce data overhead.

In a study on post-quantum cryptography’s effects on consumer electronics, for example, researchers point to a range of architectural fixes that could ease the performance hit from quantum-safe cryptography, including hybrid designs that combine classical and post-quantum signatures, more efficient lattice-based schemes such as NTRU and modular blockchain frameworks that shift heavy cryptographic workloads off-chain or distribute them across layers to reduce congestion.

These approaches aim to preserve security while limiting the impact of larger keys and slower verification times, with studies noting that careful protocol redesign — rather than simple one-for-one replacement of cryptography — can help maintain scalability and transaction throughput.