when it comes to hibernation... the more memory you have the longer it will take to boot from or go into hibernation.
I believe the reason is that when the computer goes into hibernation, it makes an image of whats running and stores it into your ram. so when it comes out.. it reads of the ram and restores everything, so if you have more ram it takes longer to read the ram.
im sure thats not the technical explanation but thats my understanding of it.
although i dont use Centrafuse centrafuse anymore, i found that 512mb of ram is a good compromise between bootup/shutdown time with hibernation and speed while using the computer.
256 -fast hibernate times, but too slow imho for normal windows usage
1GB- fast windows usage, but too slow hibernate times
but everyone will have their own opinion