toram copy to ram very slow with 2.6 kernel

When I use the toram option, copying the cd to ram using the 2.4 kernel happens in
a few minutes with data transfer of average about 4 MB/s. But if I try to do
the same thing using the 2.6 kernel the time to copy cd to ram is much slower,
about 45 minutes with data transfer rate of about 250 kb/s. This is using knoppix 3.6.
I'm using the same cheatcodes in each case, the only thing I change is to use knoppix26
instead of knoppix. Cheatcodes I'm using are:
toram nodhcp home=/dev/hda2 noapm noagp acpi=off dma config=scan
Motherboard has serverworks LE chipset. Knoppix all works great after booting
from 2.4 kernel.

Does anyone know why it's so slow with the 2.6 kernel? Can you tell me how to get
it to work?

Couple of extra points:

1. there are known problems with the ide interface in serverworks chipset; so I plugged in
a promise tx2 udma card to drive the disks, get exactly the same behviour - fast copy to
ram with 2.4, very slow with 2.6

2. I tried using 'atapicd' cheatcode in 2.6 but made no difference

Very puzzled.