SOLVED !
This problem started after I installed a iocrest pcie card with 4 sata 6b ports (marvell 9235).
Taking out the card, cd boots fast. Card in place, cd boots very slow when connected to intel-ports.
First workaround: Connecting cd to marvell 9128 port, it boots fast !
Did not like this as final solution, so searched for other solution.
Found final workaround:
Setting bios setting for "XHD" (extreme hdd) to enable. This seems to be for Raid, but I dont use raid at all. A fresh boot, and windows found new hardware, asked for drivers, I pointed to intel ahci-drivers, and it installed ok. After this the cd boots fast on intel-port and also on gigabyte ports. !!!!
Problem solved !!
Can anyone explain ??