How would the bullet kill Renard slowly?

I dunno, but was expecting Bond to kill him by using some method that would make the bullet move in his head.. No doubt the shaft thru the chest worked just fine tho!

Made up movie caca, maybe fragments of a bullet/shrapnel but not an entire bullet which would have killed him where they displayed it in film [hell he would have gotten lead poisoning to his brain if it was left in that long]

And no he wouldn't have gotten faster, fought harder and less pain and all that other bull shaite M said, he would have gotten more confused, seizures and full blown brain aneurysm.

This is one of the most annoying things about this movie:
1) If you are going to use terms like Medulla Oblongata then at least show the bullet moving through it on the scan (the image shows it moving through his right frontal cortex and heading towards his hypothalamus, they cut off his brain stem in the diagram that would include his medulla)
2) If it was moving through his Medulla Oblongata he would be losing such useful things as his respiratory centre.
3) It wouldn't move unless his daily routine is to push it further in.
4) Finally if you are going to make this stuff up then make use of it. It is only really referenced in his losing connection with Elektra, in his final fight with Bond he winces and reacts to his blows.

No one knows. Just consider it a plot hole

The bullet in James Brady's head from the Reagan Assassination attempt took twenty-five years to kill him.

The brain is among the softest tissue in the human body. A hard body (like a bullet) can tear through the tissue easily, or it could sit still for a while until something else jars it.

Definitely not a plot hole but that was already confirmed.