IBM Link: LRUD process consuming CPU
Why is the LRUD process using large amounts of CPU? Additionally, poor backup performance is seen on the AIX client when this is running.
The LRUD (least recently used daemon) is a process that is invoked when memory is low and more is needed, the daemon scans cached file pages (the buffer cache) in memory and freeing those that have not been recently accessed. When this occurs, overall performance on the host machine may be degraded.
To alleviate the problem, consider adding additional real memory and evaluating the paging space set for the host. AIX best practices recommends that there be multiple paging spaces, all equal in size and located on different, non-busy hard drives (hdisks).