Looks like the efficiency cores must be pretty weak (if we are to assume these numbers are right)
Yeah, Intel was declaring that these new Gracemont cores are as fast as Skylake, but later is kind of became clear that what they really meant was "as fast as Skylake SMT thread"... so eight of these cores are more or less equivalent to a quad-core Skylake 6700HQ or similar, which is not too bad actually.