Effective Capacitive Loading of Active RC Integrator

Question

For a simple active RC integrator shown above, what is the effective capacitive load when output is open-circuit.

I think it would be the integrating capacitor, \$C_I\$, because of the virtual ground at \$V_x\$.

But it doesn't really make sense since \$C_I\$ is charged by input current, not the opamp, so the opamp doesn't "see" the integrating capacitor.

Answer 1

But it doesn't really make sense since \$C_I\$ is charged by input current, not the opamp, so the opamp doesn't "see" the integrating capacitor.

Incorrect, the input current flows into the resistor, through the node Vx, through the capacitor and into the op-amp output. Therefore the op-amp load is \$C_I\$.