Topic: 1.5TB SD Card Concerns

I decided to invest/impulse purchase the 1.5TB SanDisk Ultra microSD... directly from Western Digital, I feel is relevant to exclaim that I have no reason to doubt the memory card to be 'genuine'.
With that said; I have noticed a reduction in performance of my Switch in general since installing the 1.5TB card.
Before this I was using the 1TB version of the same brand card and didn't really notice any issues, or differences in loading speeds compared to the 512GB card before that...
I've upgraded my Switch's storage quite a few times since I first got it.
I knew going into using the 1.5TB card that I may encounter some performance issues, but I have always though that the hardware in the Switch wasn't capable of utilising the theoretical maximum speeds any of the cards I've used so far should be capable of anyway, so I have never given it any thought.
But, as you may be able to tell from my making this post; I am a little concerned about the unignorable drop in performance I have encountered with this latest upgrade.

I'm not completely fully versed in storage devices, and have always relied on the advice of others for my knowledge in this subject.
However, due to the rarity of information on using the current highest capacity storage in the Switch I am unable to diagnose the cause of my issues, or accept that this is normal behaviour with my specific combination of devices.

My question is of a technical nature, and hope someone who knows about this subject can chime-in and offer some insight into weather the behaviour is normal and acceptable, or it can be changed to improve things.

Specifically would formatting my 1.5TB card with a different cluster size make a difference?
Currently it is set at exFAT with a cluster size of 512 kilobytes... as formatted by the Switch itself.
If I were to increase (or decrease) the cluster size by reformatting it on my PC, would that do anything productive?

Currently the performance of my Switch is pretty slow... not unusable... but not great.
And if I am downloading and running a game at the same time loading times are quite significantly increased, especially when starting game up from the consoles main menu.
Also, the "All Software" menu takes quite a lot longer to open and populate the icons than with any other memory card I have used before this one.

Any advice or just confirmation that my Switch is behaving as it should in my particular setup would be greatly appreciated.

Thanks in advance.

I forgot to mention a couple of details:

Firstly; my Switch is not modified.
It's just a regular retail console (Mario Red & Blue Edition) I purchased from Nintendo directly.

Also, the download speeds aren't constant.
If I access the download progress of an actively downloading title the estimated completion time changes a lot, and sometimes the progress bar moves quickly and then slows again sometimes as though it isn't moving at all.
But, I know the Switch is downloading data because if my console is docked I have a USB Ethernet adapter and I can see the access LED working when it is.

I didn't know if that information would be useful to anyone who has thoughts on the subject, but it's there if it is.

A game's load speed, I think, is a reflection of the card's read speed, no?

Eshop servers are not always consistent. Game downlaods can be delayed or can be slower if there's a lot of server traffic. Late at night typically has more consistent download speeds, I think.

I was thinking the something like that.

And if the current 1.5TB card design is the cause, and this is normal behaviour; I can accept that.
I was just curious, because I didn't experience such degraded performance with the 1TB option.
Maybe the density of the electronics is significantly more of an effect on the performance than I estimated.

Although 1,649,267,441,664 bytes of data storage capacity is an astonishingly large amount for something the size of my fingernail.
And I also know that the write speeds of the 1.5TB memory cards are really low.

Thank you for your thoughts.

I am still curious if anyone has any experience or insight about the cluster size, or if messing with that setting will affect anything.
I've been living with this memory card for a few weeks now, and I'd rather not waste the literal days of downloading it took to get all of my content on it again... which re-formatting to change the cluster size will inevitably result in.

I'm not sure about the 1.5 TB cards - I did experience a strange issue with a 512gb card. It worked great for about a year or so, and then stopped loading games or taking forever to boot up, followed by horrendous load speeds in game. I formatted, and all worked fine. I recently upgraded to a 1 tb card, no issues. Did you format the card first? I am far from an expert here, just sharing something that helped me.

Different cards have different speeds. Nothing to do with capacity. For Switch you want something that says V30 on the card

Just adding in my experience here on this, I had played a long time on a SanDisk ultra 1tb card and also thought there should be no different going from the 190mbps of the ultra down to a SanDisk 150mbps 1.5tb card but wow.... Loading up a save in tears of the kingdom went from being a 10 second matter up to around 30 seconds and it's not just loading that's a problem from this card, if you go from the overworld down into the depths you can even have it where the depths do not load up fast enough and link will just be frozen in the air for a few seconds before they pop in around him. It's very jarring to the immersion of the game.

I moved totk Back to the system memory for now and it's night and day different. Sad to go back to my 1tb card and I guess I'll stick the 1.5tb in the steam deck and hope it has more to do with the combo of card and switch.