If Zed would not exist, I would be using helix, neovim, or emacs as I did before.
It remains to be seen if Zed can avoid that though.
If you don't feel that VSCode is slow, it's because you are used to it.
I don't think this is a fair claim. When you start doing an apples to apples comparison, that is to say make full use of IDE and auto-completion features it's difficult to see a difference given that the latency and speed of the plugins starts to dominate any millisecond difference in input latency or rendering speed.
This is simply not true. There is inherent latency in any rendering pipeline, and VSCode and Atom both have input latency that is significantly higher than other editors like Sublime Text owing to a bloated rendering pipeline. You can read more about this and how easy it is to introduce latency simply by changing basic things like keyboards here: https://danluu.com/input-lag/ or editors specifically: https://pavelfatin.com/typing-with-pleasure/