What data cards are you using?

[Watoh]

SanDisk Extreme 32GB SDHC UHS-I Class 10

 

[ajsorrell]

I use Sony 8gb 94mb/s cards and think I will buy a couple more since the price is so much lower than I paid before:

Amazon.com: Sony 8GB SDHC Class 10 UHS-1 Memory Card (SF8UX/TQ): Computers & Accessories

 

[bobonit]

I have 2 of these: SanDisk 64GB SDXC Memory Card Extreme Pro Class 10. I got them from B&H SanDisk 64GB SDXC Memory Card Extreme Pro Class SDSDXPA-064G-A75

 

[NVSteve]

I'm using 7 of the 32gb Sandisk Extreme Pro cards, primarily because I did not want to have any sort of bottlenecks that might cause me to miss out on one of those killer shots that might actually be a money shot.

 

[§am]

specifically their Extreme 16GB SDHC which is rated at up to 45MB/s.

It's also worth noting, that the particular card you use there, is UHS-1 compatible as is your D5100.
UHS-1 class cards have a minimum 50MB/s write speed, so your D5100 will actually be making use of that higher write speed instead of the 45MB/s speed it's rated at if used in a Class 10 compatible device.

 

[Horoscope Fish]

It's also worth noting, that the particular card you use there, is UHS-1 compatible as is your D5100.
UHS-1 class cards have a minimum 50MB/s write speed, so your D5100 will actually be making use of that higher write speed instead of the 45MB/s speed it's rated at if used in a Class 10 compatible device.

Thanks for the tip, I did not know that... I do love me those cards though!