I would imagine compiler design has become much more complex in 10 years, and a low end i3 is something like at least 3 times faster than a core duo.

I would agree if other compilers, not LLVM based, took as much to compile.

Also that is surely a side effect how they are using C++, which desperately needs modules.

Those compilers don't do nearly as much optimization as LLVM does. It's hard to overstate how wide the gap between the classical compilers you like and LLVM/GCC truly is. LLVM has no fewer than three IRs, each with a full suite of compiler optimizations (four if you count ScheduleDAG). LICM, just to name one example, runs at each stage (see MachineLICM.cpp). Turbo Pascal did nowhere near that level of optimization, and it produced unacceptably slow programs by modern standards.