I really have no idea, but I'll do a little checking. My guess is yes. The chips come in a variety of speeds. Also, in addition to having an SPI interface, they have paraell interfaces as well, and that's got to be faster, at least for reading (flash probably has a limit to how fast it can write).
I don't really see SD card and a flash chip as a good comparison. My thinking is that:
SD card:
More expensive than flash
Needs to support a file system
Can be removed and put in to another device for reading/writing