Since frozen indices provide a much higher disk to heap ratio at the expense of search latency, it is advisable to allocate frozen indices to dedicated nodes to prevent searches on frozen indices influencing traffic on low latency nodes. There is significant overhead in loading data structures on demand which can cause page faults and garbage collections, which further slow down query execution.

Since indices that are eligible for freezing are unlikely to change in the future, disk space can be optimized as described in Tune for disk usage.

It’s highly recommended to _forcemerge your indices prior to freezing to ensure that each shard has only a single segment on disk. This not only provides much better compression but also simplifies the data structures needed to service aggregation or sorted search requests.

POST /twitter/_forcemerge?max_num_segments=1