Modeling switches, such as circuit breakers or power electronic devices, as current sources implies that the on-state switch resistance Ron cannot be zero. Also, as switches are modeled by a current source, they cannot be connected in series with an inductive circuit or with another switch or current source. In such a case, you must add a circuit (R or RC snubber) in parallel with the switches so that their off-state impedance has a finite value. If the real circuit does not use snubbers, or if you want to simulate ideal switches with no snubber, you must at least use resistive snubbers with a high resistance value to introduce a negligible leakage current. The drawback of introducing such high-impedance snubbers is that the large difference between the on-state and the off-state switch impedance produces a stiff state-space model. For example, if a 1 H inductance is connected to a voltage source by a switch having a on-state resistance Ron= 0.001 ohms and a snubber resistance Rs= 1e6 ohms, the time constant L/R of this first order circuit varies from 1000 s when the switch is closed to 1 µs when the switch is open. If you simulate this circuit with a continuous solver, such a wide range of time constants requires a variable-step stiff solver such as ode23tb. The model stiffness affects the simulation speed. If the snubber resistances are too large, the solver might become extremely slow or even fail to find a solution. If you are using a discretized model, you might observe numerical oscillations if your sample time is too large.