When we moved our website infrastructure over to a new host promising ultra-fast performance powered by NVMe SSDs, we expected to see significant speed boosts across the board. Faster disks, lower latency, and better throughput—on paper, there was no downside. However, what should have been a seamless upgrade unexpectedly tripled our Time to First Byte (TTFB), baffling our team and frustrating our users. After extensive debugging, the real culprit wasn’t the hardware—it was how our environment interacted with software caching. A timely tweak to Nginx’s microcaching saved the day.
TL;DR:
Moving to a new hosting provider with NVMe SSDs unexpectedly increased our website’s TTFB instead of improving it. The issue wasn’t disk speed, but how our dynamic content interacted with server-side caching—or the lack thereof. Introducing a properly configured microcache in Nginx resolved the issue by significantly reducing response overhead. With this fix, TTFB dropped to under 100ms and user experience improved instantly.
What We Expected from NVMe SSD Hosting
Modern web hosting platforms widely advertise the performance benefits of NVMe drives. Compared to traditional SATA SSDs, NVMe devices offer:
- Higher data transfer rates due to PCIe connectivity
- Lower latency in read/write operations
- Greater Input/Output Operations Per Second (IOPS)
Our expectation was clear: faster response times, better SEO due to improved Core Web Vitals, and a more responsive interface for our users and API clients. Before the migration, we carefully backed up everything, replicated our environment, and performed trials that seemed promising at first glance.
The Reality: TTFB Tripled Post-Migration
After taking the site live on the new host, we began collecting performance metrics. While static assets were loading faster, the data told a different story for dynamic pages:
- Pre-migration TTFB: ~250ms
- Post-migration TTFB: ~780ms
Google’s Lighthouse and PageSpeed Insights flagged TTFB as a major performance bottleneck, directly affecting our scores. Users in forums and customer support started reporting slow page loads. At first, we suspected DNS propagation or warm-up issues, but the anomaly persisted.
Diagnosing the Problem
The first step was isolating what changed:
- Application code was untouched.
- Database was on the same system as before.
- Traffic levels remained consistent.
- Middleware—the stack included PHP (FPM), Nginx, Redis for sessions—was identical.
Our site mostly renders dynamic content—articles, comments, and session-specific data. Upon deeper inspection, we noticed increased CPU usage per request on the upgraded host, particularly during high concurrency. Profiling indicated that redundant PHP bootstrapping was happening repeatedly for what should have been cacheable content.
The Role of Microcaching—What We Missed
On our previous setup, we unknowingly had a very short (but powerful) Nginx microcache in place. It had been configured by a former devops engineer and was cacheing responses for just a few seconds—but that brief interval was enough to collapse expensive bursts of traffic into a handful of backend requests. The new host did not carry over that exact behavior, and every request ended up going to PHP regardless of how briefly it could have been cached.
Microcaching doesn’t aim for long-term storage; instead, it sits between the application and end-users, caching for short durations (from 1 to 10 seconds) to handle traffic bursts. On high-read, low-write pages—like articles or user profiles—this makes a tremendous difference.
Even with NVMe SSDs reducing disk bottlenecks, the spike in TTFB was due to the unrelieved pressure on the application server layer. NVMe could retrieve files faster, but it couldn’t speed up PHP’s logic or database connectivity inefficiencies. As a result, removing that safety net of microcaching made the backend much more vulnerable to slowdowns under load.
Implementing the Microcache Fix in Nginx
We restored a slightly more refined microcaching strategy using Nginx’s fastcgi_cache functionality. Here’s what we added to our Nginx configuration:
fastcgi_cache_path /etc/nginx/cache levels=1:2 keys_zone=microcache:10m max_size=100m inactive=30s use_temp_path=off;
fastcgi_cache_key "$scheme$request_method$host$request_uri";
server {
location ~ \.php$ {
fastcgi_cache microcache;
fastcgi_cache_valid 200 301 302 10s;
fastcgi_cache_bypass $cookie_session;
fastcgi_no_cache $cookie_session;
}
}
This configuration does the following:
- Caches successful (200) and redirect (301/302) responses
- Avoids caching responses with session cookies (keeping user-specific content fresh)
- Evaluates freshness every 10 seconds and invalidates accordingly
After implementing this, we restarted Nginx and flushed the server’s opcode cache. Within minutes, the backend showed decreased CPU usage, and our TTFB dropped back below pre-migration values—averaging 90–110ms across global testing locations.
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Performance Improvements and Monitoring
Post-fix, our application performance was not only restored but genuinely improved by the NVMe SSDs when paired with microcaching. We observed:
- TTFB decrease: From 780ms down to 100ms average
- CPU utilization: Nearly halved during traffic peaks
- Error rates: Dropped off significantly as concurrency bottlenecks diminished
We also integrated additional monitoring to watch caching efficacy. Tools like Prometheus and Grafana allowed us to view cache hit/miss ratios in real-time, ensuring our microcache performed as expected. Combined with log_format tagging, we started tagging logs with whether they were HIT or MISS to track behavior under load.
Lessons Learned
This experience taught us that great hardware cannot always compensate for missing pieces in the software pipeline. In particular:
- Don’t assume performance gains based solely on hardware upgrades. Disk speed is only one piece of the request lifecycle.
- Re-examine all layers of stack configuration after migration. Inherited optimizations may get lost across environments.
- Short-term caches like microcaching offer massive headroom during spikes, even without full-page caching or CDNs.
Microcaching is often underutilized and subtly powerful. Especially on high-read websites with mostly public-facing content, it can improve not just speed but resource stability.
Conclusion
Even with the promise of bleeding-edge infrastructure like NVMe SSDs, true performance comes from understanding your entire delivery pipeline. Our site’s TTFB wasn’t hurt by slow storage—it struggled due to missing microcaching logic that previously absorbed traffic surges effortlessly. Re-implementing a tailored Nginx microcache restored performance beyond our original levels and highlighted how critical caching strategies remain in today’s high-performance web environments.
If you’re facing similar challenges following a server upgrade or migration, give your cache infrastructure a fresh audit. Hardware speeds may improve one layer—but smart caching improves everything else.