Adams Bashforth integration is an option offered in most packaged ODE solvers that specialize in stiff ODEs. The method solves each integration step implicitly, but it solves the implicit equations by successive substitution, rather than by Newton Raphson. Adams Bashforth is less computationally intense that Newton Raphson, but often will require many more iterations at each time step if the equations are very stiff and non-linear. So from the standpoint of computation time, Adams Bashforth may require much more computation time. Still, the nice feature of Adams Bashforth is an easily implemented automatic error control, which is built into the ODE packages.
Chet