I'm not a video expert - more audio, but have been using Premiere for ages on and off. Sorry if I use the wrong terminology.
The main problems are:
laggy playback even with just one clip and no FX.
I've done the standard playback resolution adjustment to 1/4 and 1/2, and on Full.
I've checked/unchecked the H264 accelerated decoding in Media Preferences
turned on/off high quality playback in the playback spanner drop menu
allocated max RAM in memory preferences (29GB), optimised for performance
set project settings/general/renderer to GPU acceleration
tried random other stuff I can't recall.
Audio turns to white noise after import.
audio (embedded in video) fine in file - whatever format - avi, mkv, flv. but just becomes noise when imported. Standalone audio files are fine.
crashing while exporting
adobe support says the issue can be out-of-date driver (not in my case), here's their statement:
When does this happen?
This crash occurs when you select H.264 or MPEG4 as the export formats, or if they were already chosen as the default format. This only occurs on Windows systems that are using older Intel GPUs with QuickSync.
You can fix this issue by updating your graphic drivers, or disabling the Intel GPU.
It feels like a driver problem or some kind of device conflict. It happened during the first thing I did on a brand new machine - yes it's not a specialised video production machine but it's better than what I used to have - which worked fine.