Why Your App is Running Slow: A Guide for Founders
As a founder, one of the most frustrating complaints you can hear from customers is, "The app is running slow." It's even more irritating when your tech team responds with, "Everything is fine" or "We need to add more server capacity." At that moment, you're likely thinking:
If everything is fine, why are customers complaining?
Why don't we know about these issues before the customers tell us?
Why am I hearing the same generic responses every time this happens?
If these sound familiar, you're not alone. Many tech teams don't invest enough in performance monitoring, which is the cornerstone of proactive performance management. Let’s dive into why this happens, what to track, and how performance monitoring can save your business (and your sanity).
What is Performance?
Software performance is like your app's ability to keep users happy by responding quickly and smoothly to their actions. Think of it as a balance between how well your app handles the tasks users throw at it and the resources it has available, like the servers, memory and internet speed it runs on.
For example, if only a few people are using the app, it might run great. But when thousands of people use it at the same time, performance can take a hit if your app isn’t prepared to handle that kind of load. It’s like a coffee shop: with one or two customers, service is quick, but if a big crowd comes in, things can slow down unless the shop is equipped with enough staff, supplies, and space to handle everyone efficiently.
What does the Performance problem look like?
Imagine it like a traffic jam: if one car (a user request) breaks down or stops, all the cars behind it (other requests) get delayed too. Even after the stuck car moves, everyone else is still slowed down. The real fix is figuring out why that car got stuck in the first place, not just building a bigger road.
That’s why adding more servers is like throwing more lanes on a highway without checking why there’s traffic in the first place. It might work for a while, but the problem will keep coming back.
So, if you want to improve your application’s performance, you first need to measure it.
As Peter Drucker famously said:
“What gets measured gets improved.”
Common Reasons for Performance Problems
Here are the usual suspects:
1. Inefficient Coding
Bad business logic
Unoptimized database queries
Memory leaks
Choosing incorrect data structures
Lack of caching
Serial instead of parallel processing
2. Configuration Issues
Misconfigured load balancers
Incorrect thread pool settings
Improper memory allocation
3. Insufficient Resource Capacity
Overloaded CPU or memory
Disk I/O bottlenecks
Network latency
4. Environmental Factors
Third-party service delays
Security issues like DDoS attacks or malware
Sudden spikes in user activity
Key Metrics to Monitor
To proactively address performance problems, track these metrics regularly:
1. Latency
The time it takes for a request to be processed and responded to.
Lower latency = better user experience.
High latency can result in fewer page views, lower customer satisfaction, and lost conversions.
A study shows that every 1-second delay can result in:
11% fewer page views
16% decrease in customer satisfaction
7% loss in conversions
2. Throughput
The number of requests your app can handle per second.
High throughput ensures your app supports peak traffic without breaking.
3. Error Rate
Percentage of failed requests.
A rising error rate is a red flag indicating issues in code, infrastructure, or dependencies.
4. Resource Utilization
How efficiently your app uses hardware (CPU, memory, disk, network).
Avoid over- or under-utilization to control costs and maintain performance.
5. Tail Latency (For Future proofing)
Focuses on the slowest requests, often at the 95th or 99th percentile.
Critical for identifying outliers that impact user experience.
Why Tail Latency Matters?
Tail latency represents the slowest 1%, 0.1%, or 0.01% of requests. While it might seem negligible, these outliers often signal deeper issues. If not addressed, tail latency can grow, leading to noticeable performance degradation for all users in the future.
Where to Start/What to measure
Here are some metrics to monitor:
For Web Applications
Track:
Page Load Time
API Response Time
First Contentful Paint (FCP)
Largest Contentful Paint (LCP)
Error Rates
Network Latency
Uptime/Downtime
Session Duration and User Engagement
For Mobile Applications
Track:
App Load Time
Time to First Interaction
Crash Rate
Battery Usage
Network Latency
API Response Time
Error Rates
Session Duration and User Engagement
For Backend Systems
Track:
Request Rate
Response Time
Error rate
Throughput
Resource Utilization
Database Query Performance
Disk I/O
Network Latency
Tail Latency
Uptime/Downtime
Benefits of Performance Monitoring
Proactive Issue Detection
Identify problems before customers complain.Better Resource Utilization
Avoid overpaying for underutilized hardware.
Avoid facing outages from over-utilization.
Improved User Experience
Faster, more reliable apps lead to higher customer satisfaction and retention.Informed Decision-Making
Make data-driven decisions to scale resources or optimize code.
Remember, if your team isn’t monitoring performance, start today. It’s the difference between guessing what’s wrong and knowing exactly how to fix it.
Do you need any help regarding this? Message me on LinkedIn.