Incorrect threading could be killing your app
If your app’s performance keeps dipping under pressure, your first instinct might be to blame the infrastructure. Maybe you’ve checked the API calls, ruled out database lag, and thoroughly checked your hosting. But, if you still can’t isolate the issue, it might be time to look inward. Let’s look at your code base, how is it handling large tasks?
Apps are either single-threaded or multi-threaded. Multi-threading is a programming technique that allows apps to run multiple tasks at the same time. Done right, it can keep your interface smooth and responsive. Done wrong, it can turn your app into a ticking time bomb. In brownfield environment, it can be unclear how these threads were introduced, or whether they were ever coordinated properly, but the mess needs untangling.
Not every app needs multi-threading, it’s only necessary for handling large tasks. For instance, a standard ticketing app would be better off single-threaded, as multi-threading would just add unnecessary complexity. But, if your app is performing large tasks in the background and you still want to keep your UI working smooth, multi-threading can be useful. Crucially, multi-threading has to be done in a way that is clean and organised. Anything less than that? You’re in for a mess.
We often see apps where threading has been scattered across the codebase with no real structure. Usually, in apps with a lot of moving parts or high fidelity graphics where multi-threading is needed and justified, but not implemented correctly. Shared resources aren’t protected, memory isn’t released when it should be, and the app’s behaviour becomes erratic under extensive load. Even a single race condition - where two threads clash as they access the same data - can lead to crashes that only really show up in live environments. It’s performance instability, but it’s invisible until it’s too late.
When multi-threading is mishandled, the signs eventually surface. Apps freeze when users start queueing up, inputs are delayed, background tasks hang indefinitely, features that worked in testing now break under strain. If you utilise load testing, this might even give you false confidence if it doesn’t account for concurrency issues buried in the code. At this point you’re kind of operating blind,
All anyone wants is an app that’s used and loved by many - that’s the goal! But, as your app’s usage grows, so does the risk. With every new session, the app juggles more tasks. If those tasks aren’t coordinated, the whole system begins to wobble. Developers end up chasing elusive bugs, QA time goes through the roof, and user trust takes a hit - all because of problems that started with a few unchecked threads.
We often hear it from clients: “it worked fine before”, or “we’ll tidy it up later.” There’s a common belief that adding more threads means better performance - that the more things your app can do at once, the faster it’ll be. That’s just not true. In reality, that only works when each thread is properly isolated, monitored and aligned to the app’s actual logic.
Another risky assumption is that testing caught everything. But most test environments don’t replicate real-world concurrency. You won’t see the effect of a slow connection, or the chaos caused by an old OS paired with background sync. By the time the app hits production, the damage is done and it’s often too late to patch your way out of it.
The fix isn’t more threads, thank goodness! What you need is better visibility.
The good news is, performance issues tied to multi-threading can be fixed without tearing everything down. But, it starts with an audit. A proper inspection of what your code’s doing in the background. You need to know which threads are being created, what they’re accessing, and how they interact with each other.
From there, it’s about restructuring. Reducing concurrency where it’s not needed, tightening control around shared resources and making sure tasks are queued and completed predictably. Often, this also means replacing old patches with reliable logic, simplifying flows, and stress testing under real-world scenarios.
Once the underlying issues are addressed, your app becomes more stable, more predictable, and far easier to scale. The crucial bonus? Your team can spend less time reacting to problems and more time building forward.
Are hidden threading issues slowing your app down?
Multi-threading isn’t bad tech necessarily, but poor or unchecked multi-threading is. If your app’s starting to feel unpredictable under pressure, it’s time to take a closer look at what’s running in the background. Should your single threaded app be utilising multi-threading? Or, is your use of multi-threading actually causing race conditions?
Our comprehensive audit can help you identify threading issues fast, and build a path out of performance purgatory.
Drop us a line here, we’ll help you find out what’s really going on.