Does anybody knows what's the best performance the MicroSD Card can achieve on the Desire?

Is there any hardware limitation? e.g. fastest is only 15MB/s.

On my Desire running on Reflex S 2.1.7, SD Tools benchmarked my 2GB MicroSD Card that came with the phone reach 6.4MB/s-Write; 12.2MB/s-Read. After I've increased the throughput readahead to 3072kb.