I'm working on a project where I need to apply LFU on the the value for each key. Value is something x. Now while adding value for that key, I need to delete those which has been used very less. We can use the sorted set of the dragonFly here like zpopmin, zincrby to increase the frequency of each x in the value list but this operation is taking K iops if we increase frequency of k x. How to optimise this?