I find that D is far less effort to write equivalent functionality then C++ with reasonable perf. See the links in https://forum.dlang.org/thread/[email protected]

It is also possible for D to be as fast as C++ in many domains: we have LDC based on LLVM for optimisation (parity with clang), but I think that one of the biggest things is the flexibility to have (and determine what is) an efficient architecture.