Room correction filters can be very long (thousands of samples) when correcting low-frequency room modes. This length adds latency and can cause audible pre-ringing — a faint 'chirp' before transient sounds. Impulse shortening truncates the filter while preserving the essential low-frequency correction.
The trade-off: shorter filter = less precise bass correction but lower latency and fewer artifacts. This is why many room correction systems offer 'linear phase' (long, precise) and 'mixed phase' or 'natural phase' (shorter, less precise but lower latency) modes.