docs(latency): link OpenChainBench public Solana DEX quote latency benchmark

[Flotapponnier]

Summary

Adds a short subsection at the end of portal/latency.mdx linking to a public, multi-region benchmark of Solana DEX quote APIs. The page already documents Jupiter's own gateway regions and colocation guidance; this reference gives integrators an independent way to compare quote latency from their own region before committing to colocation.

What it links to

OpenChainBench / solana-dex-quote-latency — an open-source (ChainBench/openchainbench) probe run from Paris (eu-west), Virginia (us-east) and Singapore (ap-southeast). It:

• Calls the quote API on Jupiter, Raydium, OpenOcean and Mobula every 60 seconds from all 3 regions.
• Publishes p50 / p95 wall-clock request latency and success rate.
• Rolls up 24 h / 7 d / 30 d views with methodology and raw JSON.

No API keys, no signup, no paywall.

Why here

This page is the canonical answer for "where is Jupiter's API fastest for me?". A single-line reference to a neutral, open benchmark lets integrators cross-check their own numbers instead of relying purely on ping tests to the gateway regions.

Notes

• Diff is 4 lines, 1 file.
• I don't work at any of the providers on the benchmark; happy to reword if the phrasing reads as promotional.