Costco's website suffers from slow load times due to several compounding technical issues. The platform runs on legacy infrastructure that wasn't built for modern web performance standards. Their product pages load dozens of high-resolution images without progressive formats like WebP, server-side rendering is minimal, and JavaScript bundles are monolithic rather than code-split for faster initial paint. The site relies heavily on third-party scripts for payment gateways, membership verification, analytics platforms, and advertising pixels. Each external request adds latency, especially when these scripts load synchronously and block rendering. Costco's dual business model (warehouse plus online) means their backend systems integrate physical inventory checks in real-time, which adds database queries that slow page generation. Content delivery network usage appears limited compared to competitors. Pages often serve from central data centers rather than edge locations closer to users, increasing time-to-first-byte particularly for Canadian shoppers connecting to US-based servers. Their mobile experience is worse because the responsive design downloads desktop-sized assets then scales them down rather than serving appropriately sized images. Large retailers like Costco often operate under different constraints than typical e-commerce sites. They prioritize preventing outages during high-traffic events, maintaining compatibility with internal procurement systems, and meeting legal requirements for pricing accuracy. Performance optimization gets deprioritized when sales remain strong despite slow speeds, and their membership model creates lock-in that reduces churn from poor UX. At Ottawa SEO, we've seen similar patterns with enterprise clients where organizational structure prevents rapid iteration. Multiple stakeholder approvals, rigid development cycles, and fear of breaking checkout flows slow performance improvements. The fix requires Core Web Vitals audits, image optimization pipelines, critical CSS extraction, and moving to edge computing, but implementation takes executive buy-in and significant development resources. Costco likely knows their site is slow but hasn't allocated budget to modernize it comprehensively.