Earlier quoted context omitted.
Try https://starship.rs then. Starship gives you the same "drop in and go" experience but without the 200ms+ prompt lag. One curl -> one line in your rc file, works on zsh/bash/fish/whatever. Configuration is straightforward and easy imo: https://starship.rs/config/ Give it a spin, I think you won't regret it.
I tried using Starship, and it’s clearly faster than Oh My Zsh, but my issue was that I relied on some useful Oh My Zsh features that I didn’t know how to replicate in Starship. One of these is history filtering - for example, when I type source and press the up arrow, I only see previously run source commands, which makes it easy to find what I’m looking for. I tried to get this working in Starship, but had no luck.
I don't know if starship is still using Zle. If so, this should be possible to configure without OMZ.