I'm currently running RasPlex on a 4GB SD card and the menu is very sluggish. RasPlex reccomends an 8GB card so I'm thinking of upgrading to see if that solves the issue. I think they recommend class 10 but I can't find this anymore.

So I have two options, one is to buy a cheap Strontium class 10 from an online store in my country which will arrive reliably and soon. The second is to a buy a similarly priced class 10 UHS-I toshiba card off eBay which could take over a month to arrive and is just more hassle.

So does anyone know if it's worth going the UHS-I route? Does it make a difference to the RPi or are there other limiting factors that make the performance difference irrelevant?

  • It very unlikely that going from a 4GB to a 8GB SD will make menus less sluggish. CPU, GPU, or memory limitations would be more likely candidates.
    – Gerben
    Nov 20, 2013 at 14:23
  • @Gerben The RasPlex guys do explicitly state that a 4GB card will have sluggish menus when compared to an 8GB card. I think it's a caching issue. I just want to know if a UHS-I card has any advantage over a class 10 card on a pi.
    – Dan
    Nov 20, 2013 at 14:25
  • If they use the SD card for a cache then more space will almost certainly make a noticeable difference. But how much faster a card can be really be on the pi, as per my answer, is limited. The best thing would be to use an external HD or USB stick and configure RasPlex to use that for caching, if possible.
    – goldilocks
    Nov 20, 2013 at 14:55
  • @goldilocks external HD is not an option. But a flash drive could be... can I just image the OS straight onto the flash drive? Are flash drives faster than SD cards?
    – Dan
    Nov 20, 2013 at 15:09
  • 2
    Evidently the USB bus is capable of higher speeds than the SD card reader, and googling around I see some people saying they get 30 MB/s with a stick. Regardles, if you can configure where the cache is, it might be worth trying anyway -- then you won't need a bigger card.
    – goldilocks
    Nov 20, 2013 at 15:43

1 Answer 1


I'm assuming the issue is that RasPlex is cataloging while it creates the menu? Yet this is in reference to a 4 GB card, which seems like a pretty small source to catalog. If it's just a GUI interface that is generally slow, welcome to the pi; it has the horsepower of a really low end smart phone. I.e. this very likely has nothing to do with the card. However...

Before you do anything, you should at least benchmark your current card using this test, keeping in mind that if the card is slowing things down in this context, it's because of the read speed.

On that chart of benchmarks, there are UHS-1 cards from Patroit, Sandisk, and Sony. Notice they all have about the same read speed, ~20 Mb/s. Also notice that this is the same speed as most of the class 10 cards, and, in fact, that no one has reported read speeds significantly faster than that for anything. If you look just above that test, there's another chart about what cards work on the pi, and some of those are UHS-1 cards with casual reports of read speeds (beware, the numbers in that chart are not speeds -- but look in the notes). Again, nothing above ~20 MB/s.

When I got the pi I tested two cards, a class 4 and an class 10, and while there was an appreciable difference in write speed,1 the read speed is identical (~20 MB/s). If you have a look at this thread, some one explains this in terms of the limitations of the card reader itself, which makes sense.

So if you get the 20 MB/s read already, buying a better card won't improve on that. I just tried the same benchmark with a USB (spinning disk) hard drive, and got 31.9 MB/s write and 27.5 MB/s read. Thus you could try moving the system files to an external drive, which might speed some things up a bit.2 Keep in mind though, the most frequently used chunks of system get cached in RAM anyway. Also beware that you'll likely need a powered USB hub to run an external drive (or a drive with it's own power supply).

1 Subsequently I tried a Sandisk class 10, which has twice the read speed of the Adata, but still the exact same read.

2 I don't recommend this because, TBH, I think it's pointless for this purpose. It's also a tad complicated.

  • I think it is cataloging (well, it's caching metadata like pictures and music etc) which I why I want to try a bigger card. I don't doubt the speed of my current card, I'm pretty sure it's class 10. I think from the tables you posted, I should probably worry more about the convenient card being made by Strontium (not benchmarked) rather than the fact that it's not UHS-I. I think I'll go with the Toshiba off ebay. Thanks.
    – Dan
    Nov 20, 2013 at 15:05
  • From the date of your answer, I infer that above statements were made for Raspberry Pi 1. Does the speed maximum of 20MB/s (even with UHS 1 or 3) still hold true for the new Raspberry Pi 2 B? Feb 24, 2016 at 14:17
  • 1
    @SergeStroobandt This issue has come up a number of times beyond here and a few times I've looked casually for why exactly this is the case -- my recollection is it has to do with the SD card reader hardware itself, but I can't give you a definitive set of references about that. In any case, as far as I've observed here and from using the 2 B, it's the same SD card controller with the same limitations. If it was something they'd improved upon they'd presumably brag about it, but I have not seen that either.
    – goldilocks
    Feb 24, 2016 at 20:59
  • Something to consider is that the I/O ports on all pi models aren't going to much exceed 20 MB/s anyway, so there is not a great value to having very fast primary storage unless you were processing local data under somewhat peculiar circumstances. Unless the primary storage were via USB, in which case the SD card speed is not likely to be a bottleneck. E.g., I'd guess if you wanted to transfer stuff from one USB device to another you might be able to do it at 50-60 MB/s +, but then the SD card isn't involved.
    – goldilocks
    Feb 24, 2016 at 20:59
  • @goldilocks You are right! There is no speed improvement with model 2 B over model 1. I got my question also answered here. Feb 24, 2016 at 21:43

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