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The speed will be limited by the SD card. If I recall correctly, they're not that fast.

More accurately the speed will be limited by the micro-sd card, which really aren't that fast.

You can get high capacity, high speed SDXC cards that will be just about as fast as a 5400 rpm drive, but the micro-SDXC cards max out at 64GB and are still pretty slow (though faster than most USB thumb drives).

This summer SanDisk released a micro-SD card that's supposed to be pretty fast (about as fast as a 7200rpm drive if you believe the stats), but I think max capacity is only 16GB.
 
I am currently having an 120 GB SSD and I want to store my iTunes library on that kind of drive. Do you think I will sense any kind of lag ? IMO streaming is not rocket science.
 
I am currently having an 120 GB SSD and I want to store my iTunes library on that kind of drive. Do you think I will sense any kind of lag ? IMO streaming is not rocket science.
Things will load slowly but once the media is buffered it will play fine.
 
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