Please share profiles on the list. Without known problematic production workloads, it's very hard for us to optimize appropriately. You mention predicate evalua

Please share profiles on the list. Without known problematic production workloads, it's very hard for us to optimize appropriately. You mention predicate evaluation - it's possible this won't be affected by these changes (the index internals use lower level accesses than generic expression evaluation). Re prefetching: PG does that for bitmap index scans, if you enable effective_io_concurrency > 1.