Actually I see blueprint as artist friendly. Programmer meanwhile see blueprint and use it as well. But I agree a programmer should be able to use C++ too at least whenever issues like this arise (access to engine code or performance). Using just blueprint for the entire software and call it slow is a bit lazy - sorry no other words can convey this. However, I suspect the ‘slow’ blueprint can be optimized too. Slow can also mean the author uses deferred rendering (vr is better off with forward rendering). It means arts are also not optimized too.