The PS3 used SPU threads for audio mixing. The PS3-to-PS4 wrapper emulates this via the PS4’s processor. Expect a 200ms audio delay in every title except the top 5 listed above.
Some of the top PS3 to PS4 packages that have received great reviews include: ps3 to ps4 pkg top
For those with a jailbroken PS4, there is a technical method to run PS3 games using the via a Linux payload. The PS3 used SPU threads for audio mixing
The Ultimate Guide to PS3 to PS4 PKG: Everything You Need to Know ps3 to ps4 pkg top