I also had huge problems with it, and indeed LSP support is why I use neovim these days and not vanilla vim. I probably had problems similar to what you did: sometimes it'd work, often it wouldn't. And it was SO slow. I'm also using recent, powerful hardware: top of the line MacBook Pro, 16 core / 64 GB RAM Linux workstation, both on SSD/NVME storage. Once I switched to the built-in LSP, all my problems disappeared. I'm pretty happy with my current setup, and videos are hard for me to follow for tech stuff, but others who aren't already may want to look at the video.

I should point out that even this repo reinvents things that are already in vim: you don't need packer. Vanilla vim has package management now, all you need to do is put the plugins in a directory under ~/.vim/pack/whatever/start. See :help packages for more.