Speaking in crude terms that don't exactly apply to brains…
>The heart rate and breathing PWM/oscillator circuits would run too fast
>The average adult human brain dissipates 20 W and is can run safely at 37.5 C but can't handle temperatures even a few degrees higher for extended periods
>Getting to bullet time speeds in a standard computer with a clock speed equivalent to that of the human brain with comparable functionality would let the magical smoke out
>There'd probably be way more memory leaks than usual because you'd have to reduce capacitances in the neural circuitry (memory leaks occur when a capacitor inside of a memory cell of a computer discharges, setting the bit from 1 to 0)
What I'm getting at here is that you'd not only need to significantly change the fundamental structure of the brain on a sub-cellular level, but your brain would melt like a rabid animal.