Your customers say the app is slow. Lists stutter when they scroll, the app takes ages to open, and now and then it freezes. Your developer says "that's just React Native", and you can't tell if that is true or an excuse.
This guide explains React Native performance in plain words for the person who paid for the app. You will see what "slow" means in numbers, where Google Play and Apple show you those numbers, and what a good developer checks before blaming the tool.
Quick answer
Is React Native laggy?
No, not by design. The official React Native documentation says phones show at least 60 frames (still pictures) per second, so the app has about 16.67 milliseconds to draw each one. When the app's code is busy for longer than that, a frame is dropped, and people see a stutter.
What "slow" means in plain words
Customers describe three different problems, and each has a different fix:
Ask your customers which one they mean. "The app is slow" alone sends a developer looking in the wrong place.
How do you measure React Native performance?
You don't need a developer to see the first numbers. Google Play Console shows them under Android vitals, and Apple shows them to your developer in Xcode Organizer. Both use real data from your users' phones, not a test phone on someone's desk.
Android vitals: Google Play's official limits
Google Play Console Help lists these as "bad behavior" thresholds, as of October 2026.
| What Google measures | Plain meaning | Bad behavior threshold |
| User-perceived crash rate | Share of daily users who saw the app crash | 1.09% or more overall |
| User-perceived ANR rate | Share of daily users who saw the app freeze | 0.47% or more overall |
| Crash or ANR on one phone model | Same, for a single phone model | 8% or more |
| Slow cold start | Opening the app from scratch | 5 seconds or more |
| Slow warm start | Reopening it from the background | 2 seconds or more |
| Excessive slow frames | Sessions where most frames are late | More than 50% of frames late |
| Excessive frozen frames | Frames that take very long to draw | More than 0.1% take over 700 ms |
Crossing the crash or ANR limit can make your app less visible on Google Play. Google says it may steer users away and may show a warning on your store listing.
Apple's numbers for iPhone
Apple's Xcode Organizer shows your developer launch times, memory use, how quickly the screens respond, and battery use. The data is anonymous and comes from real users. Ask your developer to send you a screenshot each month.
Why does a React Native app feel slow?
The common causes are about how the app was built, not the tool. The official React Native documentation names several of them. Here they are in plain words.
Testing the wrong build
Developers test in "development mode", which is much slower because it adds extra checks and messages. React Native's documentation says to always test speed in a release build, the version your customers install. A judgement made on a development build is not a fair test.
Leftover debug messages
Developers print messages while building, called console logs. React Native's documentation warns that these can cause a big slowdown in a live app, and should be removed before release. It is a quick fix, and a good first thing to ask about.
Too much work at the wrong moment
Most of the app's own logic runs on one "JavaScript thread" (a single line of work). If that line is busy loading data or doing sums while the person scrolls, frames get dropped. Moving animations to the phone's main screen thread avoids this, as React Native's documentation explains for screen changes.
The JavaScript engine
React Native uses an engine called Hermes by default. Its documentation says that for many apps this gives faster start-up, lower memory use and a smaller app. If your app is old and was never upgraded, ask whether it still uses Hermes.
If you want an outside check of a slow app, read about The Beyond Horizon's mobile app development service for Indian businesses.
What does a developer check during app performance optimization?
A good developer measures first and changes code second. The steps below are a fair order of work. Ask for each one by name.
- Read the Android vitals and Xcode Organizer numbers, and note which ones are above the limits.
- Install the release build on a cheap, older Android phone as well as a new one.
- Find the two or three slowest screens, using what customers actually complain about.
- Check the quick wins: debug logs removed, Hermes turned on, React Native version not far behind.
- Fix the worst screen first, such as a long list or a heavy animation, and measure again.
- Release the update and watch the vitals for a few weeks before starting the next fix.
A real example: smooth animations in Kerbcop
Kerbcop is a parking app we built in React Native and Expo for Parking Services Ltd in New Zealand. Its animations run on the phone's UI thread using React Native Reanimated, at 60 frames per second. This is the same idea the official docs describe: keep motion off the busy JavaScript line.
How long does React Native performance work take?
It depends on what the first measurement shows, so nobody can give an honest date before that step. Quick wins like removing debug logs are small jobs. Rebuilding a slow list or a heavy screen is a bigger one.
Pay for the check first
Ask for the measurement step to be quoted on its own. You then know the size of the React Native performance problem before you pay for the fix. A developer who refuses to measure first and wants to start rewriting is a warning sign.
Should you fix the app or rebuild it?
Try fixing it first. Speed problems often sit in a few screens or habits, while a rebuild means paying for the whole app again. Ask for a rebuild only if the developer can show, with numbers, that the base of the app can't reach the limits above.
Questions to ask before you pay for speed work
A small tip most owners miss: ask for a short screen recording of the slowest screen before and after the fix, on the same cheap phone. It is easy to compare and hard to argue with.
A short note before you decide
The Beyond Horizon has delivered 40+ projects across websites, apps and custom software. A speed problem is easier and cheaper to fix when it is measured before anyone changes code.
If your React Native app feels slow and you want it checked, call or WhatsApp The Beyond Horizon on +91 75973 92744.