We found our site was slow in Singapore but perfect in Europe — here's why

Source: Dev.to

Problem

We thought we were doing everything right. Our API was behind Cloudflare with edge caching, and our dashboards showed sub‑100 ms p95 response times. After a customer in Singapore reported that the API took 4–5 seconds to respond, we assumed the issue was on their end. Our monitoring, however, was only checking from Frankfurt, so we were blind to the performance experienced by the 40 % of traffic coming from Asia‑Pacific.

Discovery

When we added health checks from Singapore, Sydney, and Tokyo we found:

• DNS resolution: 800 ms+ (our DNS provider had poor APAC coverage)
• SSL handshakes: 400 ms (no session resumption across regions)
• Connection setup: the main bottleneck, even though the first byte from the origin was fine

These issues had been affecting users for months without us noticing.

Root Causes

• Limited monitoring locations: Most uptime tools check from only 1–3 regions (typically US East or EU West).
• Regional internet variability: Outages and performance differences can be highly localized.
• DNS propagation: Not instant or uniform across the globe.
• CDN cache hit rates: Vary by point‑of‑presence (PoP).
• ISP peering agreements: Can create routing inefficiencies.
• SSL verification: Slower in regions with poor connectivity to OCSP responders.

Impact

• User experience: Slow responses caused users to abandon the site.
• SEO: Google’s Core Web Vitals (LCP, FID, CLS) are ranking factors and are measured from crawlers worldwide. Poor performance in APAC lowered our scores, hurting rankings globally.
• Business: After fixing APAC performance, LCP improved by ~0.4 s and competitive keyword rankings rose within six weeks.

Solution

We built Latency Global, a monitoring system that checks from 70+ locations worldwide and alerts on regional degradations.

Setup

1. Add the URL.
2. Select the regions to monitor.
3. Set the check interval.

The entire configuration takes about five minutes.

Benefits

• Cache warming: Periodic checks keep DNS caches, CDN edge caches, SSL session tickets, and TCP connections warm, turning a cold start of ~2 s into ~200 ms for real users.
• Performance gains: Measured a 40 % improvement in Time‑to‑First‑Byte for regions with active monitoring.
• SEO improvement: Better Core Web Vitals scores across all regions.
• Peace of mind: Detect slowdowns before customers notice them.

Takeaway

If your monitoring only checks from one region, it’s giving you a partial view. Global monitoring not only reveals hidden performance problems but also provides unexpected advantages such as cache warming, SSL session persistence, and SEO improvements.

Regional performance issues are silent killers—users don’t complain, they just leave.
Global monitoring has unexpected benefits—cache warming, SSL session persistence, and SEO improvements.
Cloudflare/CDN ≠ guaranteed global performance—you still need to verify what users actually experience.

If you’re curious about how your site performs from Singapore, São Paulo, Sydney, or any other location, give it a try—you might be surprised.