  The cosmic evolution of a dark matter model which behaves relativistically in
the early Universe is explored. Dark matter is described as a complex scalar
field, whose earliest evolution is characterized by a stiff equation of state
($p \simeq \rho$). In this phase, it is the dominant component in the Universe.
We present constraints from Big Bang nucleosynthesis and primordial gravity
waves from inflation. Also, we study how the associated enhanced expansion rate
due to the stiff phase might facilitate a first-order electroweak symmetry
breaking phase transition, in light of the recently measured value of the Higgs
boson mass.
