PERF.63 Website: a distributed crawl of /roadmap-issues filter combinations is about half of all PHP page requests (485,944 in 8 days, 172 ms and 1.4 MB of HTML each)

Access logs: 485,944 requests to /roadmap-issues in 8 days (184,651 on Nov 6); in the last 5 hours 24,548 requests from 17,356 distinct IPs with browser user agents and fake referers, every permutation of ?app=&channel=&kind=&layer=&release=; 23,831 of the last 49,776 dynamic requests. Each costs 172 ms of PHP, 23 queries and 1,416 KB of HTML (112 KB gzipped): about 23 CPU-hours and 54 GB of egress in 8 days, invisible on /admin/analytics because Analytics::SKIP_PREFIXES has /roadmap-issues. The crawl ignores robots, so per-IP throttling cannot help. Change: render the item list once per release into Cache (60 s) and filter from it (172 to about 20 ms); rel="nofollow" on every filter link and a canonical URL per release; if the page stays reachable by link, filter client-side on the cached list. Removes about 45 % of PHP CPU and most HTML egress today; the page gets 8x cheaper for staff.