Typically see that when there is high spec and/or bump and strong lighting made worse by the scattering ( assume the high contrast increases the convergence time)

Can't see the bump or spec map so based on my experiments with the Amy texture with the above node set-up

1. Check bump map has a gamma value of 1
2. Check spec map has "use Gamma value from Render settings"
3. Try turning off the bump completely to see if that improves it

Based on the second render would agree the spec map looks too bright.