There's a kernel driver; Xbian's
mount-ntfs is presumably a user space one, but the former is a different implementation. I would guess it will consume less resources when you are not actually doing anything with the partition.
However, it may not be available on Xbian. Unmount the drive and try instead:
mount -i -t ntfs /path/to/partition /mount/point
This should avoid invoking the userspace driver because of
-i ("-i, --internal-only: Don't call the [userspace] helper even if it exists <-
man mount). If you don't get any errors, check
ps -A | grep mount. There should not be any such process running; it will exit right away having invoked the kernel driver if present.
If there is such a process, it's probably the same thing as
mount-ntfs. If not, the partition should be mounted and available.