Your Nvidia card won't need a layout-id for the HMDI audio.
Any slow down is likely to be caused by a clash with another kext you have installed, like VoodooHDA.kext.
Your motherboard according to this specification page -
https://support.lenovo.com/gb/en/so...-5474-6232-m90p-3282-3652-5450-5498-5852-6590, uses the Realtek
ALC662 codec.
The Realtek ALC662 codec, according to the supported Codecs page for AppleALC.kext, requires one of these options to be set in your config:
- 0x100101,
- 0x100300
- layout-id 5, 7, 11, 12, 13, 15, 16, 17
Using this boot argument:
alcid=x,
where x = 5, 7, 11, 12, 13, 15, 16, 17 would probably the easiest way for you to test and set the id. As it would be easy to change if you need to test each id, to see which works best with your Lenovo system.
Remember that when you are looking to check to see if any audio devices are working that you need to select the device in the System Preferences > Sound > Output preference pane, as shown in the screenshot below.
You will need to test the device(s) using the Sound Effects tab, with the device selected as shown below, Otherwise you can miss the fact the device is actually working.