The first thing a person with a slow phone does is install an optimizer app with a promise to free up memory with one tap. The second thing they do is close all open apps by swiping them away from the multitasking screen. Both actions make the phone slower, not faster, and the reason is how memory works in modern systems. Let's figure out what actually slows down the device and what can be done about it for free.

Why Optimizers Are Harmful

When you minimize an app, the system does not leave it running at full power, but suspends it, sharply reducing memory consumption while at the same time maintaining the ability to return to it instantly. This is intentional, and the principle is formulated so that free RAM is wasted memory. The system keeps recently used apps in memory precisely so that switching between them is instant. When an optimizer forcibly unloads these apps, it destroys exactly the mechanism that makes the phone fast. When opened next time, the system loads the app again from storage, spending more CPU resources and more time, that is, what could have been an instant return turns into a full launch. The situation gets worse if the optimizer cleans memory automatically, since the phone gets into a vicious circle where apps are closed, you open them again, they load, and a minute later they are closed again. A side effect is accelerated battery drain. An independent study by the AV-TEST institute showed that a significant part of the most popular cleaner apps in the Google store did not provide any measurable performance improvement, while at the same time requesting excessive permissions, including access to contacts, location, and storage. Google, by the way, took on this category directly. In Android 14, software interfaces that such apps relied on to forcibly terminate background processes were restricted, and store rules now directly prohibit developers of such programs from making misleading claims about their usefulness. The typical operating scheme of such programs was to show a frightening result of a fake scan with a message about a critically low level of memory and dozens of threats found, after which the user was offered to fix the situation by subscription.

Why Swiping Away Apps Does Not Help Either

An app that is hanging in this menu mostly does not use either CPU time or battery charge, since it is suspended, and its very presence there only means that it is ready to be quickly restored. Force-closing makes the system load everything from scratch the next time it starts, which consumes more energy and more time. The exception is a specific app that is obviously behaving incorrectly, that is, heating the phone, quickly draining the battery, or freezing, and it is worth closing that one.

About Clearing the Cache

The cache exists so that the app works faster, storing locally what would otherwise have to be downloaded again. Clearing the cache frees up storage space, but the next launch of the app will be slower until the cache is formed again. On modern storage devices, several thousand temporary files do not have a measurable effect on speed, so the idea of a phone filled with junk that slows it down is mostly a myth on which the sale of cleaners is built. Clearing the cache makes sense only for a specific app that is working with errors, and precisely as a way to eliminate a malfunction, not as a regular procedure.

What Actually Slows Down the Phone

Full storage really harms performance, since flash memory sharply loses write speed when little free space remains. A practical guideline is to constantly keep at least fifteen percent of the total capacity free, that is, approximately nineteen gigabytes on a device with one hundred and twenty-eight. Below this threshold, saving photos, installing programs, and any file operations become slower. A worn-out battery is the second common reason, since when the battery condition deteriorates, the system may intentionally reduce processor performance to avoid sudden shutdowns. On iPhone, the battery condition is visible in the settings, and a figure below eighty percent means that replacement will solve not only the problem with battery life. Overheating leads to a temporary reduction in processor frequency, and that is why the phone slows down in the sun, during a long game, or while charging in a warm room. Background activity of apps really consumes resources, and here we are not talking about suspended programs, but about those that constantly update data, track location, and synchronize. An outdated system version means the absence of optimizations that the manufacturer added later, so updates more often speed up the device than slow it down. The growth of the apps themselves is a reason that is rarely considered. Your phone has not become slower, but the apps you use have become heavier, and on a five-year-old device this is felt most strongly.

Malicious software also has this effect, and a classic sign is a combination of sudden slowdown, rapid battery drain, and an unexplained increase in data usage.

What to Do Step by Step

Start with storage by checking how much space is left free, and if it is less than fifteen percent, freeing up space will have the greatest effect among all actions. Videos, photos, and messenger caches usually take up the most space, and it is from these that you should start. Telegram and similar apps store all viewed media files locally, and their folder often takes up dozens of gigabytes. Delete apps that you do not use, and check whether there are any duplicates by purpose among them. Restart the phone, and do this at least once a week, since restarting clears accumulated errors and frozen processes without any third-party programs. Check for system updates and install them. Limit background activity for specific heavy apps through the built-in settings, not through third-party programs. On Android, this is done in the settings of the specific app in the battery section, while on iPhone, in the general settings there is a separate item about background app refresh, which can be disabled completely or selectively. Check the battery condition and replace it if the capacity has decreased significantly.

Turn off or reduce animations in the settings, since this does not technically speed up the system, but noticeably reduces the waiting time between actions. Delete all previously installed optimizers, cleaners, and accelerators.

When Only a Reset Will Help

If the phone slows down after all the listed actions, a full factory reset remains, and it really helps because it removes accumulated remnants of programs and settings from years of use. This should be done only after a full backup, and it is worth understanding that some data, in particular two-factor authentication apps, requires separate preparation, which I wrote about in detail in the material about transferring data to a new phone. A reset will not help if the reason is a worn-out battery or the fact that the device is simply outdated for modern apps.


Sources: AV-TEST research on cleaner apps, Android developer recommendations on memory management, MakeUseOf publications, Bitdefender