Forum rules
An Activity Log is required for support requests. Please read How-to get an activity log? for details on how and why this should be provided.
I'd also note, the release 2.7 does not contain this. Only development builds do. We only use official releases of x265.
I would suspect unless they find any problems, x265 2.8 will contain these and we'll probably upgrade sometime after they release it once the dust settles and it appears stable.
Most cases <10% improvement. It's also not currently available on mainstream CPU's. We need to wait for cannonlake to be released by Intel for that so benefits will only be for those who have certain Xeon / Core i9 CPU's for now.