Is there a big difference between the Balanced and Best Performance power modes in Windows 10?

There is no universal percentage difference between Balanced and Best performance on Windows 10. The result depends on the processor, OEM firmware, cooling, battery state, and workload. Balanced still allows the CPU to increase speed when work requires it, while Best performance tells Windows to favor responsiveness and higher performance more aggressively. That can shorten battery life, raise temperature, and increase fan noise. On many brief office tasks the measured difference may be small; sustained compiling, rendering, or other CPU-heavy work can show more benefit, although thermal limits may erase it. Modern Standby does not standardize this gap. To test your model, run the same task three times in each mode with identical power source, battery level, background applications, and room temperature. Compare completion time, not just clock speed, and record battery drain and temperature. Use Balanced normally, and choose Best performance on AC power when the measured gain matters.