Yes clang used bootstrap in a similar time to its contemporary GCC version and compile code notably faster at the cost of emitting slightly less optimised code. Over the years LLVM became bloated. It's now by far the biggest and slowest to compile part of the FreeBSD base system, but there are only two useable open source C and C++ compilers and GCC isn't acceptable to the existing userbase because they changed their license to GPLv3. Also modern GCC isn't nearly as small as GCC 4.2 used to be.