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Do SD Cards Slow Down Phones?

Do SD Cards Slow Down Phones?

Unlike iPhones, most other phones including Android smartphones allow you to expand your internal storage through micro SD (Secure Digital) cards. If you use one on your micro SD card-supported phone, does it slow down your device?

See also: Can A Phone Work Without An SD card?

Do SD cards affect phone performance?

Whether an SD card can affect your phone’s performance depends on what is stored in it. Apps installed on the card will generally slow down your phone, whereas simple data will not as much. 

Aso, a low-speed, unbranded, or older SD card can badly slow down the phone, whereas a high-quality card will generally give you smoother and faster performance for apps and data. 

An SD card can affect the performance of your Android phone particularly if you have moved lots of apps or games to the card. In such a case, the OS needs to continually read and update apps and games on the card.

As a result, the loading, sync, and refresh speeds of the apps is reduced and cause lag. 

If the SD card is low quality , the effect on the phone performance can be even worse leading to system crashes, data corruption, hanging, or even failure. 

On the other hand, a a decent quality SD card may not cause any noticeable performance issues if you use it simply to store data such as photos. 

Why does the SD card read/write cycles and speed matter?

All SD cards have a limited number of read/write cycles. Their lifespan is finite and decreases every time data is accessed on them.

An SD card of reputable brands often have  a longer lifespan than cheap unbranded cards. That’s why if you use a cheap SD card, you will notice the effect on the phone’s performance more.

Using an old SD card with a lot of past usage might also cause performance issues, as there’s no indication of how much it has been used,.  

Similarly, the effect on the phone’s performance will be more noticeable if you use a card with a low-speed rating (e.g. Class 2, 4, or 6 SD card). It’s recommended to use an SD card with at least Class 10 or UHS-1 (Ultra High Speed-1) rating for storing files and media.

For storing apps and games, on the other hand, a card with an app performance rating class of A2 is recommended. 

See the section “Do SD cards speed up phone” for more about the A2 rating. 

Does a micro SD card make a difference in terms of speed?

A micro SD card is simply a smaller physical variant of an SD card, using the same communication protocol. Most Android phones have a micro SD card slot rather than a standard SD card one.

A micro SD card can’t make your Android phone run faster than the maximum level the device can run at. It can however help your phone run more smoothly.

This means that if your phone is running at half its maximum performance, e.g. due to full internal storage, adding a micro SD card for extra space may help it attain the maximum level your phone can operate at.

You should use a high-quality micro SD card and clear some of the internal storage of the device by uninstalling unused apps, or moving files from internal storage to the micro SD card.

If you move the apps and games to the micro SD card, use apps that hold more data in the Android folder of the SD card, or move the game’s OBB (Opaque Binary Blob) files to it, the micro SD card can make a bigger difference in terms of speed. 

This will be determined by the characteristics of the micro SD card like speed rating. 

Do SD cards speed up phone?

A high-quality SD card with a high-speed rating can speed up a phone for tasks like loading apps and games if these are moved to the card. It can help the device run at its maximum level. 

For instance, the A2 app performance class SD card can perform 2000 input/output write operations and 4000 input/output read operations in one second and has a minimum write speed of 10 MB/sec.

Again, If you want to store data like photos and other files, you should have at least a UHS-1 or Class 10 SD card for adequate speed.

Does a full SD card slow down a phone?

Whether a fully packed SD card slows down a phone depends on what type of data your SD card stores.

Sometimes, you may notice a temporary slow down as you copy files from the internal storage to the full SD card while doing other tasks on your phone. In these situations, older files need to be overwritten to make space for newer files which can slow things down. 

Most of the time, however, your phone performance won’t be affected and you may not feel any difference while the files are being copied. 

A high-speed card that is at least Class 10 or UHS-1 type from a well-known brand will have higher read/write speeds so the files will be accessed or moved faster.

On the other hand, if you have moved the apps to a full SD card, it may slow down your phone a lot more compared to simply storing data on it. See “Does using SD card as default storage slow down Android phone?” further below.

See also: Should I use my SD card as default storage?

Will using a bigger memory card slow down my Android phone?

Will using a bigger memory card slow down my Android phone?

Using a bigger memory SD card will not slow down your phone. However, it should not be larger than the maximum capacity your device was designed to support.

For example, it’s not recommended to use a 256GB SD card on a device that supports only 32 or 64GB SD cards. If you do, issues may arise such as the card being detected only up to the specified maximum capacity i.e. 32 or 64GB, or the card not being recognized at all.

If a phone has support for a 256GB SD card and you insert one, it will work normally. You should be using a high-quality and high-speed memory card from a reputable brand like Kingston and SanDisk. 

Note that Android OS and certain apps like the music and Gallery app will scan the SD card on its insertion each time. The bigger the SD card is, the more time it can take for the scan, which can make the device and apps feel a bit sluggish.

Does using SD card as default storage slow down Android phone?

Default internal storage (aka Adoptable Storage) lets you run apps from your SD card, effectively letting your device use the card as part of its system storage.  This is useful if your phone is low on internal storage, preventing you from installing more apps.

Using an SD card as default internal storage on your Android phone can slow down the device. SD cards are essentially slower in speeds as compared to the device’s internal storage and have a limited number of read/write cycles.

If you use the SD card as default internal storage, there will be an increased number of read/write cycles. Thus, the SD card will degrade over time which can lead to the device slowing down.  

This can also result in the stuttering of the apps stored on the SD card along with slow data transfers.

Another factor that can slow down the phone is using a cheap or low-quality SD card. You’ll experience more frequent lagging in apps and data transfer will be slower. This can even result in the OS freezing and being forced to restart.  

Which is the fastest micro SD card?

Many Android smartphones (but not all) have slots that accept a micro SD card. The fastest SD cards and micro SD cards are those that currently have a UHS-II bus interface.

This means that these cards can attain the theoretical yield of up to 312MB/s read and write speed (aka bus speed). In reality, the actual speeds of these cards are somewhat lower.

The following table shows the top 5 fastest micro SD cards that are available currently and their rated read and write speeds (in descending order of rated write speed):

Brand & ModelRatedRead Speed(MB/s)Rated WriteSpeed (MB/s)
1Delkin Devices Power V90300250
2Lexar Professional 1800x UHS-II 270 245
3Verbatim Pro II Plus V90295245
4ADATA Premier One V90275155
5Kingston Canvas React Plus V90285

Source: Have Camera Will Travel 

The term V90 in the name of these cards denote the Video Speed class 90. Micro SD cards with such a rating have a minimum write speed of 90MB/s but can support the UHS-II bus interface.

The Video Speed class is the latest speed class of micro SD cards, aimed to support greater video resolution and recording features.