The Compressed Baryonic Matter experiment (CBM) will study rare probes in a heavy-ion environment at high interaction rates of up to 10 MHz. The observation of detached vertices requires a topological trigger, which is too complex to be defined in the hardware, and fully realized in software. Excluding conventional, latency-limited trigger architectures, CBM opted for a free-running readout. The primary beam is delivered by a slow extraction synchrotron. To be able to operate the experiment at highest interaction rates, despite beam intensity fluctuations, a time-based throttling mechanism is under study. SystemVerilog based simulations of the readout system show the feasibility of the examined throttling algorithm to reduce the number of incomplete events, particularly in presence of intensity fluctuations.