Currently, even when AHI is disabled, there is overhead of AHI during dropping of extent.
See fseg_free_extent() and the loop of btr_search_drop_page_hash_when_freed(). This iteration depends on number of extents. So if table is huge (in order of 100GBs), there is overhead by btr_search_drop_page_hash_when_freed().
PS-5576 fixed this issue partially only for truncate DDL. This JIRA issue should fix all paths leading to fseg_free_extent().