Write Speed, Virtual Memory, and SD Cards

[AC Question]

I have a Samsung Galaxy S4 mini. The internal SD card is maxed out, as I have a lot of customization built into it. However, my SD slot is completely unused, so I want to use the SD card as virtual memory which, along with overclocking, will improve the phone's performance for intensive activities.

I want to know what kind of SD card I should get for it.

1. The S4 mini is graded at maxing out 64 gb extra space, why can't I get a 128 gb one? What happens if I use that?
2. Will read/write speed matter if using the SD card for virtual memory? How much faster is the S4 mini internal read/write compared to using a card with 90MB/s read and 80 MB/s write?

 

[Rukbat]

so I want to use the SD card as virtual memory

Using the card as virtual memory slows the phone down.

which, along with overclocking

The question is whether your model S4 will take a custom kernel.

I want to know what kind of SD card I should get for it.

Always a U1. (U3 is good for 4k video, but the phone can't do that, so it would be wasted money.)

1. The S4 mini is graded at maxing out 64 gb extra space, why can't I get a 128 gb one? What happens if I use that?

It should work. A slot that accepts a 64GB card should accept up to a 2TB card.

2. Will read/write speed matter if using the SD card for virtual memory? How much faster is the S4 mini internal read/write compared to using a card with 90MB/s read and 80 MB/s write?

None. The phone isn't that fast, so the card will be faster than the phone can use it. (Speed depends on two things - how fast the card can be accessed and how fast the phone can access the card. The slower one wins. A 10,000 TB/s card won't be accessed any faster in that particular phone. It's like asking how fast a Porsche will go in a traffic jam.)