If you're trying to set it up for three users, you'd need to pay for a organization, which starts at $9/month. On the other hand, I believe you could set up two free organizations where you are a member in each, and you add your mom to one and your wife to the other.
https://bitwarden.com/help/article/getting-started-organizat...
https://bitwarden.com/pricing/business/
I don't think it was a particularly difficult process, but I did it on my computer, and once it was all figured out, helped my spouse with the rest. I don't find the sharing process confusing. You click Share on a saved password, choose the organization, and then you choose the collection you put it in (which can simply be Default.)
I haven't found BitWarden to be slow, but my laptop is a Ryzen 7 4800H and my old phone was a Pixel 3, so neither are slouches. Not sure how many records I have but I'd estimate about 500.
I'd be a bit afraid of this. Secure key derivation takes time. Remember, you want to be able to defend against people with a few GPUs or the ability to configure a cheap FPGA at least and the ability to build custom ASICs or employ a GPU botnet at worst. Taking ~5 seconds to derive your key securely on your phone is a near inevitability.
1. Sharing is super-confusing. I was trying to organize things for my mom, as well for my wife and I. And you have to create these "organizations". And they makes things really confusing for a variety of reasons. They are a different pricing/SKU. And the UX around them is not good. It's not clear where things are being created a lot of the time, and who may or may not have access. It just was a really bad experience.
2. It was outrageously slow for me. I use Enpass otherwise, and it comes up right away, and searching is relatively fast. But Bitwarden always had this delay. And it was a huge pain point because it wasn't clear immediately if there were just no results, or if I just had to wait a few seconds. And sometimes things would pop up unexpectedly.
So I've continued using Enpass. It has _by far_ been my favorite password manager. It's no open source, but it uses Sqlite and SqlCipher under-the-hood, and I have full control over where it syncs my data to. Sharing is still a problem (mainly because of the architecture decisions - there is no "central server"), but everything else is so great that I'm fine making that tradeoff.