They are long and narrow, so one would expect them to be fast, but the speed depends on other factors too. Rail, tail drag, a fin, and god knows what other laws of physics...
The size of interest is 103L, and that would be a small board for me (102kg).
I use that size in 25+ knots winds, so not much, and no point in spending '000s on a board that is used 5 times a year , but wouldn't mind something that narrow in high winds. They do have a good rap.
If anything, it could end up on the wall as a decoration