I shoot using a 7D, and normally use a SanDisk Extreme 60MB/s 16GB card. On a recent shoot I ran out of card space and borrowed an empty SanDisk Ultra 30MB/s* 16GB card (the asterisk, I'm not sure what it refers to). Looking back at the footage, all the stuff shot on 60MB/s - as usual - is great, but the footage shot on the borrowed 30 is slightly laggy, as if the frame rate has been affected.
Can someone shed any light on this? Is there anything that can be done with the footage?