I capped my Android phone’s CPU to 70% for a week; here’s what actually broke

One vital component is the CPU. It processes all the commands and instructions being sent to your smartphone and coordinates the hardware.

Even a cost-efficient smartphone needs a capable CPU to function well for everyday use, but the major trade-off is often the battery.

As someone who strongly advocates for battery-conscious practices, I did the forbidden and decided to see whether capping my CPU speed to 70% was worth it for a week — the results weren’t too surprising.

Why should you underclock your CPU?

Your device rarely uses the CPU at full capacity

The main reason to consider running the CPU at a lower speed or capping the maximum frequency is your battery.

Essentially, you avoid pushing your phone to the brink with its processing power, which saves your battery (in theory, but in practice it’s more complicated).

It can also keep your device cooler because it runs at a lower frequency than usual.

The less heat you produce, the better shape your internal components will be in. Heat is a killer for the battery.

But the catch is peak performance, and some heavy-resource apps demand more — like Google Maps, Adobe Lightroom, and more.

It depends on what kind of smartphone user you are, since some users may never notice the difference in their apps.

Cutting down CPU speed using battery-saving

I customized my battery-saving options

I cut my CPU maximum frequency and tested whether it made a difference.

I did that by turning on power saving mode on my Samsung Galaxy S25+ (One UI 8.5).

I did this for:

• Watching shows on Netflix through the Netflix app
• Listening to music in Spotify
• Launching Wuthering Waves and wandering through the first region
• Casually using a few key apps like Microsoft Teams, Character.AI, and Samsung Browser

Based on past behavior, I predicted the first three options would take a hit by reducing the CPU, while the latter ones wouldn’t be noticeable.

Also, to make the comparisons fairer, I consistently charged my device between 70% and 80% so no other battery-saving settings would interfere with my usage.

My testing with Wuthering Waves was more limited since it causes the most battery drain, followed by watching Netflix in full HD 1080p.

For Spotify, I removed my usual data saver settings, so it didn’t affect streaming quality.

For Wuthering Waves, I avoided optimization practices, so I didn’t use Game Booster through the Game Launcher on my Samsung Galaxy phone.

Still, to be safe, I changed the permissions under app settings by going to Apps > Game Booster > Change system settings.

I toggled off Allow permission.

For the other apps I mentioned, I didn’t have to worry about in-app settings that could affect my device’s CPU, so I left them as is during the test.

With Netflix, I noticed some lag right before startup. This was likely because I don’t use the app very often on my device (I am not starting from a suspended state as I do with other apps).

That’s mainly because my iPad has turned into my Netflix streaming machine outside my TV.

But after starting the app and opening it on consecutive days, I didn’t notice the lag as much — or at least it didn’t feel like a big deal after I got used to it.

The issue was when I wanted to do full HD streaming. That’s when I noticed that lowering the CPU caused unwanted stuttering and delays. It would have been a “yikes” if 4K was an option.

This is because it doesn’t have enough resources to decode high-resolution streams fast enough.

This varies based on how your device handles resources, whether it uses aggressive caching, and whether apps refresh in the background — all of which compete for your CPU resources.

Sometimes, Netflix may lower the video resolution if it notices your device is struggling with higher-resolution videos — unfortunately, this happened to me throughout the week.

I tried changing the app settings to control playback, but nothing let me do that besides controlling video playback with cellular data usage (I checked Maximum Data just in case, since I have Wi-Fi dead zones in my home).

So I quickly found out that lowering my CPU speed did me no favors.

On the bright side, Spotify wasn’t as bad because it doesn’t need to decode videos. I could listen to music comfortably without it being a major issue.

It just had CPU spikes, which made the app run a little more slowly.

I noticed this most on screen wakeups and with larger playlists (streaming from my liked songs versus imported libraries).

But at most, this was only a few seconds of delay.

Also, I don’t use playback features like Crossfade and Equalizer, which apparently can increase CPU needs.

Next up was the most brutal, and as a gamer, this is where I don’t want to sacrifice performance — that’s playing Wuthering Waves.

This game is demanding on mobile. I loaded this app onto my dedicated gaming phone and my daily driver to process subscription fees and coupons.

But, unsurprisingly, anything that requires loading/rendering a lot of 3D assets will be brutal on your device’s CPU and GPU (it hogs them).

Both of my phones already stutter in the newer regions and heat up like a furnace, so I have to play with a controller instead of the touchscreen.

In this particular case, CPU capping is detrimental, and I don’t recommend it.

I didn’t want to keep testing because the game was a stuttering mess, and I ran these tests in the first region, where assets aren’t as graphically intensive as they are in the Mengzhou region.

Fortunately, the three apps I tested didn’t matter; capping my CPU did nothing, as there were no performance downgrades.

That’s where limiting your CPU is completely fine. Browsing websites on the Samsung Browser is incredibly lightweight since I am usually just reading news, while I only use Microsoft Teams for messaging.

Character.AI’s heavy processing happens remotely, but it can sneakily use up a lot of RAM.

If I mainly use apps daily but never game or stream on my device, permanently lowering my CPU to extend battery life is totally fine if it works.

Otherwise, as a mixed user like me, do this only situationally instead of perpetually — the disruptions are more than noticeable, and I didn’t think I was really saving battery.

Forcefully capping the CPU isn’t ideal

When you reduce the CPU’s capacity to process information, you create background bottlenecks that can hurt the user experience.

Given how dependent phones have become on smartphone apps, even for deeply embedded multitasking, it’s hard to sell leaving the phone at 70% CPU unless you’re a casual, lightweight user.