Watching a flagship Galaxy phone stutter on basic tasks feels absurd, especially when the same device handles Genshin Impact at max settings. At this price point, it shouldn’t drop frames just switching between messages and a browser.
For months, I blamed Samsung’s heavy software and wrote off the occasional hitch as the price of running One UI. But the lag had nothing to do with too many background apps or unoptimized software. It turned out to be a built-in performance feature Samsung quietly turns on out of the box.
What RAM Plus actually does
Turning your phone storage into memory
That feature is RAM Plus, Samsung’s take on virtual memory. It borrows between 2GB and 8GB of your internal storage, or up to 12GB on Ultra models, and treats it as extra RAM. It’s the same concept as a paging file, something desktop operating systems have used for decades.
Where this falls apart is the speed gap. LPDDR5X memory, the kind in flagship Galaxy phones like the S25 series, runs at theoretical speeds around 51,000 MB/s. Even the fastest UFS 4.0 storage in Samsung’s top-end phones tops out at about 4,200 MB/s on sequential reads. That is already a 12x difference, and latency makes it worse. Physical memory responds in roughly 10 nanoseconds, while a storage swap takes thousands of times longer. So when you switch back to an app whose data was moved to storage, the processor has to read it back into physical RAM and push something else out to make room. Every app switch through that cycle pays the price.
You’d never guess any of this from Samsung’s own UI, though. Device Care lumps physical RAM and RAM Plus into one number, so a phone with 12GB of RAM and 4GB of RAM Plus displays 16GB as the total. That number hides a real performance trade-off.
Flash storage can’t match RAM speeds
A phone with 12GB of physical RAM can keep 15 to 20 apps loaded at once, and Android already manages that well on its own. Its built-in zRAM compresses inactive app data directly inside physical RAM, no storage involved. On a phone with this much memory, the system rarely runs out of room.
RAM Plus adds a slower layer on top of that. Even with zRAM keeping things efficient, Samsung’s software shuffles background app data to flash storage before physical memory is anywhere close to full. So instead of letting the phone use the hardware it already has, the system forces a slower path.
On my S25, I lived with this for a couple of months before I figured out what was going on. I’d shoot a photo, switch to WhatsApp to share it, and the app would reload from scratch. The keyboard would lag behind my first few taps after waking the screen. I cleared the cache, installed every update hoping for a fix, and nothing changed. The phone had 12GB of fast memory, yet it was still swapping data it didn’t need to move.
One toggle and the stutter was gone
Disabling virtual memory restored real speed
High-end phones run best when the operating system isn’t stacking extra layers between apps and physical memory. RAM Plus sits under Device Care > Memory, where it reserves internal storage as a swap file. Turning it off prompts a restart, since the system can’t reconfigure memory while Android is still running. Once the phone came back up, that storage was free again, and the interface lag vanished.
Samsung didn’t always make it this easy. When RAM Plus first arrived with One UI 4 update in late 2021, the system forced a permanent 4GB allocation with no built-in way to disable it. Enthusiasts had to tether the phone to a computer and run developer commands in a terminal. It wasn’t until One UI 5, after widespread complaints about stuttering on high-end devices, that Samsung finally added a proper on/off toggle. They heard the feedback and gave users a way out, yet they still ship the feature enabled by default on every new Galaxy phone.
There’s also a cost you won’t notice day to day. Flash storage has a finite number of write cycles, and virtual memory eats into that limit by constantly moving background data on and off the disk. On a phone you plan to keep for three or four years, that kind of disk thrashing adds up.
Who should actually turn it off
If you have a budget Galaxy with 4GB or 6GB of RAM, keeping RAM Plus on might still make sense, since the extra virtual pool can hold one or two more apps alive in the background. But on any phone with 8GB or more, it’s the first setting worth turning off. Samsung markets the combined number as a feature, a bigger total that implies better multitasking. That number was the thing slowing my phone down.
