Disclaimer: While we are using tax season and fintech applications as an example in this blog, the insights and strategies discussed apply to any Node.js application experiencing high traffic periods.

Tax season is here, and with it comes one of the most intense periods for fintech apps. If you work on a fintech app, you’re already familiar with the challenges: high transaction volumes, a surge in user activity, and the critical need for precision. But as your app becomes a lifeline for users navigating their finances, it’s vital to ensure your backend can handle the pressure.

Recently, we hosted a webinar discussing exactly this—how fintech companies can prepare for tax season and optimize their infrastructure for real-time monitoring and scalability. The discussion highlighted real-world experiences, key technical insights, and best practices for ensuring that your app remains reliable under high loads.

This blog expands on those insights while retaining all the original best practices we had planned to share. You can find the full webinar recording embedded below:

https://www.youtube.com/watch?v=ZoIgbjwUXAs&t=365s

Why Tax Season Is a High-Stakes Period for Your App

Tax season brings unique challenges that demand your app’s full attention. Key pressures include:

Surge in Usage: Users logging in simultaneously, querying data, and processing transactions all at once. This can lead to slower response times or downtime if your infrastructure isn’t prepared.
Regulatory Compliance: Accurate reporting and strict adherence to financial regulations are non-negotiable. Tax filings rely on the precision of your app, so even minor errors can have significant consequences.
User Expectations: Your users demand real-time updates, lightning-fast performance, and unwavering reliability. A poor experience during this high-pressure time could damage your reputation.
Infrastructure Strain: Resource-heavy processes, such as server-side rendering (SSR), can push your backend to its limits during peak traffic, potentially slowing down your app or inflating operational costs.
Privacy and Compliance Constraints: Managing sensitive financial data means you likely deploy on-prem or operate your own AWS/Kubernetes clusters. This ensures privacy and compliance, but it also increases the responsibility to optimize and scale your infrastructure without relying on external PaaS tools.

Each of these challenges underscores why tax season is a high-stakes period: your app’s performance, reliability, and compliance aren’t just expected—they’re critical. Preparing your backend to handle these demands isn’t just about avoiding failure; it’s about meeting the heightened expectations of a user base that needs you to perform at your best.

Challenges in Enterprise Node.js Applications

1. Scaling Efficiently with Kubernetes

A massive issue during periods of high traffic is that applications suddenly become unresponsive, and Kubernetes clusters randomly kill pods due to hitting resource limits. This is a recurring challenge that many companies struggle with at scale.

A key insight we’ve observed is that Node.js behaves very differently from other technologies, especially in Kubernetes. Kubernetes abstracts physical infrastructure, while Node.js operates with logical resources. This fundamental difference causes friction—Kubernetes attempts to scale, but Node.js believes it’s still operating fine.

Surprisingly, even experienced teams managing large-scale, real-time systems weren’t fully aware of this conflict. Many organizations struggle to align Kubernetes’ scaling methods with Node.js’ runtime behavior, which creates additional performance bottlenecks.

2. Memory Management Issues

Node.js relies on the V8 engine’s garbage collector, which dynamically expands and retains memory based on demand. Unlike traditional applications, V8 does not immediately release memory after use—it only does so when absolutely necessary. This behavior often leads to confusion, as a sudden spike in memory usage does not necessarily indicate a memory leak.

A common mistake many organizations make is killing Node.js processes when memory usage spikes, assuming the application is misbehaving. However, this can lead to unnecessary downtime and instability. The key takeaway is that high memory usage in Node.js is not inherently bad—it’s often just a reflection of how V8 optimizes performance by retaining memory.

Additionally, Kubernetes environments often enforce strict memory limits, which can cause Node.js applications to hit artificial constraints and get forcefully terminated. This misalignment between how Kubernetes manages physical resources and how Node.js handles logical memory allocation is a frequent cause of performance issues.

To avoid disruptions:

Monitor the heap rather than overall memory usage to determine actual memory constraints.
Use proper autoscaling mechanisms that account for Node.js's memory behavior instead of relying on default Kubernetes settings.
Optimize garbage collection settings when necessary, but avoid premature tuning without proper profiling.

Optimizing Node.js in Production for Tax Season

Fundamentally, your team must ensure your infrastructure can scale effectively to handle the surge in traffic without compromising performance or escalating costs.

Below are key strategies for optimizing your infrastructure:

1. Optimize SSR Workloads

Server-side rendering (SSR) enhances user experience by delivering pre-rendered content, but it can be extremely computationally expensive. SSR is inherently slow on Node.js because it’s a CPU-intensive operation: during rendering, the event loop gets blocked, preventing the runtime from accepting and processing other incoming requests.

To avoid overwhelming your backend:

Cache frequently accessed pages to reduce the number of SSR requests.
Use hybrid rendering strategies, where static content is pre-rendered and dynamic content is fetched only when necessary.
Offload non-critical SSR tasks to background workers during peak periods.

Many companies overspend on SSR due to inefficient scaling, turning it into a cloud money pit. Most cloud architectures lack a deep understanding of how to scale SSR efficiently, leading to unnecessary compute costs and performance bottlenecks. Instead of throwing more resources at the problem, strategic caching and smarter rendering approaches can drastically cut costs and improve scalability.

Note*:*

The best way to mitigate the blocking nature of SSR is to cache as much data as possible.

A highly effective caching solution is Valkey, an in-memory data store that delivers excellent performance. It's the perfect companion for a Node.js application. The Node.js driver supports a technique called autopipelining, which automatically batches all operations during an iteration of the event loop into a single network request—without requiring any changes to your code.

Next.js natively supports custom cache handlers for applications. By implementing that interface, you can use any storage system you prefer to manage your server's cache.

Usually, you would need to handle this complexity yourself, implementing the cache handler, managing key uniqueness, and ensuring data is shared across instances.

However, when using Watt and the @platformatic/next service, all of this is handled for you. All you need to do is update your watt.json file to include the new cache settings.

2. Implement Efficient Caching Strategies

Caching is a powerful tool to maintain high performance under heavy loads. Caching should not be an afterthought but a core design decision for scalable apps.Focus on:

In-memory caching for frequently accessed data to minimize repetitive database queries and reduce API load.
Caching at various layers, such as HTTP caching and database query results.
Make use of cache invalidation strategies to ensure data accuracy while reducing load.

We’ve seen cases where teams realized their Kubernetes cluster was underutilized or badly used inside a cluster due to a lack of effective caching. Their system was processing excessive duplicate requests because they hadn’t implemented a proper caching layer, which resulted in unnecessary resource consumption. After optimizing caching, usually by writing a custom algorithm, they can reduce their cloud spend significantly.

Whether it be using our Open Source toolkit to synchronize your local cache, or using our Intelligent Command Center (ICC) to handle the distribution, synchronization, and orchestration of cache invalidation across your entire ecosystem, Platformatic is here to help with caching. We offer:

Client-side caching using HTTP standards for a familiar and fast experience
Synchronization of local copies across servers to ensure consistency across distributed environments
Seamless invalidation across local and distributed caches to eliminate the risk of stale data being served and remove the burden on developers to implement and maintain complex invalidation mechanisms

3. Balance Microservices and Resource Allocation

As companies scale, many adopt a microservices architecture to increase flexibility.

However, assigning micro CPUs to Node.js processes is often counterproductive, as Node.js performs best when running on full CPU cores.

Additionally, Kubernetes' generic scaling mechanisms do not always suit Node.js applications. Over-fragmenting applications into microservices can lead to excessive inter-service communication, adding unnecessary complexity and latency to the system.

Organizations should carefully evaluate their microservices architecture to balance flexibility with efficiency.

4. Conduct Load and Stress Testing

A little bit of slowness in the system can have a massive domino effect. As such, it’s important to keep an eye out, monitor and test.

Often, we see teams go through multiple test runs but still underestimate the true strain that peak traffic would bring. Everything seems stable in controlled tests, but when actual users flood the system during a critical deadline, database queries slow dramatically, and activity failures skyrocket. The team then has to scramble, purchasing extra cloud resources at a premium cost to stabilize the situation.

By the time things stabilize, the damage was already done—frustrated users, delayed filings, and a scramble to allocate more cloud resources at a premium cost.

To avoid this scenario, ensure your system is resilient before peak periods:

Simulate real-world traffic surges by increasing concurrent users, transaction volumes, and background processes to uncover potential bottlenecks.
Monitor database performance under stress to determine whether queries need optimization or indexes should be added.
Test response times, database performance, and API throughput.
Identify any single points of failure or bottlenecks in your infrastructure that could lead to downtime or slow performance.
Load balancers are an essential component of horizontal scaling. If you are deploying on your own hardware, you will need to make sure your traffic can be balanced effectively over as many application instances as you have available. If you’re running on Kubernetes, you’re likely going to rely on your Ingress for load balancing, but there may be cases where you want to use per-service load balancers.

Note*: Kong is a popular option for providing more control and visibility than the default Ingress Controller. If you’re running on bare metal you may want to consider HAProxy.*

Thorough preemptive testing allows teams to identify vulnerabilities in a controlled environment rather than scrambling to fix them during a crisis.

5. Monitor Your Infrastructure in Real Time

Real-time monitoring is crucial to staying ahead of performance issues before they impact users.

However, standard metrics for Node applications often lack the context needed for effective troubleshooting.

Monitoring Node.js performance requires cobbling together insights from multiple tools and custom dashboards, juggling metrics like CPU usage, memory consumption, and latency. This fragmented view makes it difficult to pinpoint the root cause of slowdowns and unresponsive applications.

Imagine a platform with numerous microservices; a fragmented view might reveal high CPU usage, but without context, identifying the culprit remains a guessing game. This hinders timely troubleshooting, leading to persistent performance bottlenecks that cost companies millions in lost revenue.

Note*: Platformatic offers a single, intuitive dashboard that gives teams a real-time overview of all their Node.js applications and services so they can see resource utilization, deployment statuses, and key metrics like CPU usage, memory consumption, latency, and event loop utilization in one place.*

By centralizing all application data and activity in one place, the Command Center provides a comprehensive audit trail. This facilitates compliance efforts and helps trace actions for troubleshooting purposes to minimize user impact.

6. Enable Dynamic Scaling

Static infrastructure configurations often lead to inefficiencies during periods of high demand. Take advantage of dynamic scaling to adjust resources in real time based on demand:

Set scaling policies based on key metrics such as CPU, memory, request rate, or custom application-level metrics.
Consider load balancing strategies to ensure traffic is distributed evenly across servers to prevent overload on any single instance.

Once again, in the past, we came across a company relying on default Kubernetes autoscalers that struggled with sudden traffic surges, leading to bottlenecks and service delays. Switching to an intelligent autoscaler reduced unnecessary costs and improved response times, ensuring a seamless experience even during unexpected traffic spikes.

Note*: With Platformatic’s Intelligent Autoscaler, your application will dynamically adjust Kubernetes resources in response to traffic spikes and Node-core metrics, ensuring optimal performance and uptime.*

By contextualizing Node.js and its applications within clusters, the autoscaler intelligently measures event loops and intelligently handles concurrent requests with precision, allowing applications to stay responsive and efficient, even under varying loads– no hands needed.

A Note on Cloud & Serverless

Cloud and serverless architectures introduce another set of challenges.

AWS Lambda, while often marketed as a solution for effortless scalability, comes with strict invocation limits that can cause bottlenecks in high-traffic applications. If these limits are not configured correctly, a sudden traffic spike can overload the system, leading to unexpected outages. Companies moving to the cloud must fully understand these limitations and design their applications accordingly to avoid costly disruptions.

Wrapping Up

High pressure periods, such as tax season for fintech apps, presents a significant challenge, but with the right strategies in place—such as optimizing caching, balancing microservices architecture, understanding serverless limitations, and real-time monitoring—you can ensure a smooth experience for your users.

By proactively preparing your infrastructure now, your app can confidently navigate periods of high demand, delivering reliability and performance when it matters most.

Tax Season Survival Guide: Preparing Your Node.js App for High Pressure Periods