Advice on a more robust Installation

Hi All... I'm new to setting up immich. It's been about two weeks. I've set this up on my DS923+ NAS and I'm going through the initial import of 50K photos.

I've had to baby Immich through the whole import process every few hours for the last two weeks. I've had to pause the later tasks and even though immich shows the functionality to run concurrent tasks. The only way it's seems to make any progress is if i pause everything except one type of task. (ie all the metadata extract, then all facial recognition.. etc.. )

All the time it's tied up my NAS so it's basically useless and crashing my other containers, plex and other tasks. I've tried to be very patient but all this watching closely isn't really practical and I have probably another 50k of photos in external folders that it hasn't started yet.

My question is, can I time these scans to off hours and limit processors and RAM so I don't have to watch everything so closely? And does it really have to take a week+ of processing power and time?

Maybe i'm looking more for commiseration here but i'm finding all the effort i need to expend here rather frustrating.