Sure, but is that using PCHs? And how much of that time is preprocessing? I don't think the parent question is whether clang can compile any project in less than 3 hours. I think the interesting question is if warp is more compelling than clang from a preprocessing perspective.
I mean, I do too, but they take even longer with gcc. I can remember when compiling could take a full day. These metrics mean nothing without comparison. Clang is hands down the fastest c/++ compiler I've ever used.
I know of a project that takes around 3 hours to build with Clang when you do a "make all".