I'm in the process of picking out my first mirriroless camera and I found some storage on sale it was an eight dollar difference to get the high-performance a Card am I really going to notice a difference? I do want to shoot some video and I read some things That say video shooting maybe better with a high-performance card any thoughts on that anyone?
Me being a penny pincher I was tempted to save the 8 bucks haha
There are two types of speed... card type, and ... well I guess card speed.
Newer card types are faster, but the camera should support that type. You can just buy the card type recommended in your camera manual. You should at least get that card type.
Newer cards will have faster specs, and they will be backward compatible with our cameras, and they will work, but more type than our camera implements will not be useful to the camera. Except it is possible that you might have a newer card reader, and it may still be faster in the reader.
And then there is card speed. Within a given type of card interface, maybe SDXC UHS-1, different cards have different speed ratings. Normally read is faster than write. The camera only writes, the card reader normally only reads.
If you shoot JPG, a 24 megapixel image is only about 12 MB. If you shoot one each second, that is only 12 MB per second needed for card speed. If you shoot continuous 5 frames per second, that is 60 MB/second. What is the point of a 95 MB/second card? (except at the card reader).
But if you shoot Raw, the files are much larger, maybe 22 MB. Then 5 fps becomes 110 MB/second, and if you do more than a second or two (buffer), you may want all the card speed you can get.
But you can buy a card faster than the camera can write. I have Lexar X1000 cards, but my D800 can only write about 70 MB/second, so some of the speed is wasted. Except that it is rather fast in the card reader.
You can time your current speed.. Time the writing of a continuous burst mode of maybe 5 or 10 raw images. Time the green card access LED. Then multiply for total MB written, and divide by seconds, MB/second.
And in the camera, extreme card speed is only a factor for shooting continuous raw files. For single raw files or even continuous JPG, not much speed is really needed. But again, downloading a couple hundred of them in the card reader does make us think about speed.

Our card reader should be USB 3.0 and should handle the card type. But we should realize why we are buying speed. One JPG every few minutes has no use for much card speed.
Movie mode is even slower yet. Much smaller images, and the card has the length of the movie to write it, and any Class 10 card is plenty for movies. Except again, there is the card reader.
