LLVM / Clang git for libclc: optimized build or debug?

[Dieter Nützel]

make[1]: Leaving directory '/opt/llvm/bindings'
llvm[0]: ***** Completed Debug+Asserts Build
llvm[0]: ***** Note: Debug build can be 10 times slower than an
llvm[0]: ***** optimized build. Use make ENABLE_OPTIMIZED=1 to
llvm[0]: ***** make an optimized build. Alternatively you can
llvm[0]: ***** configure with --enable-optimized.
304.322u 15.792s 1:50.25 290.3% 0+0k 6156432+1518784io 942pf+0w

Second:
'make -j 4' do NOT work in the first run. --- Known?

It breaks with 'killed' not known.

Thanks,
   Dieter