  In the simplest model of magnetic pairing, the transition temperature to the
superconducting state depends on the dynamical susceptibility $\chi({\bf
q},\omega)$. We discuss how $T_c$ is affected by different momentum and
frequency parts of $\chi({\bf q},\omega)$ for nearly antiferromagnetic and
nearly ferromagnetic metals in two dimensions. While in the case of
phonon-mediated superconductivity any addition of spectral weight to
$\alpha^2F(\omega)$ at $\omega >0$ leads to an increase in $T_c$, we find that
adding magnetic spectral weight at any momentum ${\bf q}$ and low frequencies
($[0:3T_c]$ and $[0:(5-9)T_c]$ for nearly antiferromagnetic and ferromagnetic
metals respectively) leads to a suppression of $T_c$. The most effective
frequency and momentum range consists of large momenta ${\bf q} \sim (\pi,\pi)$
and frequencies around $10T_c$ for nearly antiferromagnetic metals and small
momenta ${\bf q} \sim 0$ and frequencies of approximately $(13-22)T_c$ for
nearly ferromagnetic metals.
