I believe the OP is talking about a file copy - which means the format doesn't matter.
Cat 5e and 6 will probably both yield the same speed for gigabit.
Theoretically if you got 100MByte/s, then 10-12gig would take under 2 mins. But there are many pieces in this puzzle including your hard drives and controllers. Should be less than 5 mins for those size files.
This is were you find out how fast your HDD actualy is in the computer that's running the server. If a laptop you can expect it to be power saving and running slow, if it's a desktop computer that may not apply. But other tasks may get in the HDD way and slow it's read time.old lap top as example.
If no trans-coding is necessary then i say about 15 to 20min.
If it's an .mkv and needs to be trans-coded then just let it sit over night.
Yes mine is about the same from PC to PC. This is more a test of the PC. PS3mediaserver Status screen has my PC DLNA serving the PS3 at a peak rate of 500 mb/s on a Gigabit network. So hardware (not Hard Drive) limitations limit it to half the theorectical max.
Steady state/average speed is much less.
By the way the PS3 OS will not support a file size above 4 gig.
actually the ps3 OS does support files sizes over 4gb. It's the external drives formatted fat32 that are capped at 4gb.
Copying a 12gb file seems to take an eternity. I was considering getting a new gigabit router and upgrade to cat 6 cables, but i'll guess i'll hold off.
I don't think you will notice much of a difference, at least not enough to make it worth spending money on new cables and a new router.
If you really don't want to wait to copy the videos to the PS3 your only other option is a media server.