Client success story
StringKick cut server latency by 52% while scaling “Duolingo for guitar”
Summary
From guitar lessons to an interactive learning platform
StringKick began as a collection of articles about musicality and playing by ear. Over ten years, founder Just Rijna expanded it into a WordPress-based education business with LearnDash courses, WooCommerce memberships and StringKick Games—interactive exercises that can listen to a student’s guitar through the microphone. As more of the experience became dynamic, fast backend response times became essential to both learning and growth.
Client
StringKick
Location
The Netherlands
Industry
EdTech
Platform
WordPress, WooCommerce
Results at a glance
The impact in numbers
Migrating to Servebolt eliminated the server response bottleneck that persisted despite extensive frontend optimization. A later upgrade to Servebolt Linux 8 further reduced measured TTFB by 52.03%, while the platform remained stable through traffic spikes and more than five years of continued growth.
294 ms
TTFB after moving to Servebolt Linux 8.
98
PageSpeed Insights desktop performance score after migration.
52%
Improvement in measured server response time.
5+
Years on Servebolt without hosting-related operational issues.
About
A guitar learning platform focused on real musicality
LEARNING MODEL
StringKick’s 90–10 rule encourages students to spend 10% of their time learning concepts and 90% actively practicing them.
COMMERCE
LearnDash courses, WooCommerce and WooCommerce Subscriptions power course access and recurring membership.
PRODUCT
StringKick Games can hear a real acoustic or connected guitar through the device microphone. Away from the instrument, students can tap the screen and continue practicing.
APPLICATION LOAD
Level completions, achievements and saved game states trigger asynchronous requests and database writes through the WordPress backend.
The challenge
The limits of previous hosting
Before migrating to Servebolt, StringKick cycled through three different hosting providers, with Kinsta being the last. Throughout that time, Just spent countless hours hyper-optimizing the website to pass Google’s Core Web Vitals checks. But frontend optimization alone couldn’t overcome the server bottleneck. Just was caught in a common hosting challenge: running a dynamic, resource-intensive application on infrastructure that wasn’t optimized for its workload, while relying on costly add-ons to support essential database operations.
Failed Core Web Vitals on Their Previous Hosting
Google PageSpeed Insights returned diagnostic alerts for the core lesson page. The site failed the Core Web Vitals assessment based on both field and origin data.
660 ms server response delay
PageSpeed Insights flagged a critical performance bottleneck: “Reduce initial server response time,” revealing a structural 660 ms server processing lag rooted in the hosting infrastructure.
Diminishing returns from frontend work
Just spent countless hours hyper-optimizing his code, tracking down rogue scripts, and shrinking image sizes to single-digit kilobytes, but those changes couldn’t overcome a high Time to First Byte (TTFB).
Business risk
A large share of StringKick’s traffic comes from organic search, and Just knew that site speed was a ranking factor. More traffic meant more students, and a slow site put a ceiling on both. Slow server responses threatened search visibility, student acquisition, and the perceived quality of the product.
Why Servebolt
Choosing based on real-world performance
Just tested copies of the real StringKick site across several hosting providers rather than relying on marketing claims. Servebolt delivered an immediate reduction in Time to First Byte without requiring any application changes. The cost was comparable to the previous managed WordPress host, making the performance difference the deciding factor.
Performance
Faster dynamic requests
Servebolt delivered faster uncached and dynamic requests—the requests behind key student actions like completing levels, saving progress, and accessing membership content.
Support
Engineering support, not scripts
While some web hosting providers have moved toward AI-driven support systems and automated triage, Servebolt has maintained a human engineering support model. During setup, Just could speak directly with senior technical leads who understood both the hosting platform and the type of application he was building.
Sustainability
Efficiency aligned with company values
As an educational platform handling a high volume of ongoing requests, StringKick’s server footprint matters. Servebolt’s focus on efficient infrastructure and green data centers aligned with Just’s preference for a lower-impact approach to running an online education business.
Operations
Flexible USD invoicing
Although StringKick is based in Europe, much of its student revenue is generated in US dollars. Servebolt accommodated USD invoicing, reducing unnecessary currency conversions and administrative friction.
Migration
A seamless transition, without disruption
Migrating StringKick was more than a simple website move. The platform relied on active student subscriptions, progress-tracking systems, and complex API connections that needed to remain fully functional throughout the transition. Servebolt managed the migration process carefully, ensuring the application moved successfully without operational downtime, data loss, or disruption to students.
Before and after
Measured performance improvements after migration
Within 28 days of the 2021 migration, StringKick’s Core Web Vitals passed, and the previous 0.66-second server response warning was completely eliminated. Later, Servebolt’s Linux 8 upgrade further reduced measured TTFB to 294 ms without requiring any additional work from StringKick.
| Metric | Before | After |
|---|---|---|
| Hosting Provider | Kinsta | Servebolt |
| Time to First Byte (TTFB) | 660 ms | 294 ms |
| Core Web Vitals | Needs improvement | Passed (98/100) |
| Traffic Spikes | Performance concerns under increased traffic | Stable response times during traffic surges |
“Switching web hosts alone brought time to first byte down that much—that’s incredible. And every time I contact support, I am dealing with an actual human expert who understands exactly what I am trying to build. Over the last two years, my support requests have dropped to practically zero – not because help isn’t there, but because the platform works so flawlessly that I never need to reach out”.
Just Rijna, Founder of StringKick
Technical deep dive
A WordPress platform with application-like workloads
StringKick combines content, commerce and interactive software. Each completed level, unlocked achievement or saved game state creates user-specific backend activity that cannot simply be treated like a cached marketing page.
Application workload
| Frontend | Browser-based JavaScript games |
|---|---|
| Backend | WordPress |
| Learning | LearnDash |
| Commerce | WooCommerce Subscriptions |
| Dynamic actions | Progress, achievements, saved states |
Why infrastructure mattered
| Uncached requests | Frequent and user-specific |
|---|---|
| Database writes | Triggered throughout gameplay |
| Concurrency | Multiple active learners |
| Product feel | Slow performance hurt UX |
| Growth | More learning paths and a native app using the same backend |
What’s next
The same foundation is supporting the next stage of growth
StringKick is adding learning paths for triads, scales, chord progressions and deeper ear training. A native mobile app is also in testing, using the same Servebolt-hosted WordPress backend so progress can stay synchronized across web and mobile.
Could your site benefit from the same performance gains?
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