Sometimes. Vanilla emacs is lightning fast, but it's also missing critical features for most people.

If you want to use emacs as a an alternative to VSCode, or IDE in general, you'll find high quality plugins that will enable you to do so. But then you might experience slow downs.

As emacs is single-threaded (people will come and tell me it's not anymore, I know, but in practice it still is) you'll feel any slow downs in those plugins. Emacs typing latency isn't great.

It's a mixed bag really. It can be fast, it can be slow. It's still my favorite editor.

For me as a long term Emacs user, started using it 1994ish, it is not an issue. I don't mind the occasional minor lag. In my usage it is rarely in a range where it actually makes me wait.

Emacs has a certain feel to it. Hard to put the finger on, but the movement of the cursor and the scrolling, it just feels nice for me. Like a well worn favourite T-Shirt.

What are you using now? If VScode or Atom you won't feel any degradation. If vim or SublimeText, some things will take few extra dozens of milliseconds. You could test the Doom Emacs, which is trying to be a feature-full emacs environment optimized for speed.

Sometimes. But, in my experience a lot of these advanced development environments can be quite hang-ey if you know what I mean. It’s quite lightweight relatively speaking so more than makes up for it.

Speaking as recent(4-5 months) Emacs(spacemacs) convert - it is slower compared to even "decked out" vim. An important caveat to mention is that it very much depends on what modes you are operating in -- each file type will usually operate in its own mode, with varying performance. In my experience the lagginess is rare, but its very workflow dependent, there's this one large(1.5k line) php file I have to edit semi-regularly on which I switch off the php mode, just to avoid the pain of jankiness. It isn't very noticeable in other, "regular" sized files.

But overall I'm a very happy emacs convert. It's extremely malleable and pleasant development environment and I think it definitely deserves all the gushing articles/posts its been receiving past few years.

I don't know the reason but for me Emacs is frustratingly slow compared to Vim.