my ntfs-3g application takes up to 20% of my cpu usage. I don't know any way to reduce it so I have to kill it's proceess. Any idea about fixing this?
I'd consider configuring spotlight not to index or monitor your NTFS partition.
If that doesn't work you might consider defragmenting the NTFS partition, disabling transparent compression, or updating to a newer version of NTFS-3G.
For more information Tuxera has a decent FAQ related to performance problems with NTFS-3G.