Twitter's web app was at that conference doing a workshop on ways to disable right-click Open in new tab.

Twitter's web version is actually using React Native for web - one of the types of technology people often expect will perform poorly

Trying to use it while logged out in a private session on mobile is an absolute joke. After the page loads, you get the "Download the mobile app" nag that takes up half the screen and that you have to dismiss. As often as not, as I'm trying to dismiss that, the "Sign in with Google" nag pops up over it and I accidentally navigate away to their SSO flow, have to hit back, wait patiently for the popup that pops up over the popup, dismiss them both, then just read the text on the page that I intended to read.

Credit where credit is due though, up until a month or two ago I'd then also get hit with the Quora-esque "Make an account to continue" nag that blocked reading if God forbid I scrolled too far down the page. When geohotz went to Twitter, I recall him saying if nothing else he would get rid of this garbage anti-feature and sure enough I've not seen it since.

On my iPhone SE the Twitter web app becomes laggy after performing a few searches and scrolling through a few lists.

Sure my phone is kinda old, but I don’t believe it has to be like this ...

Agreed. I use the web app exclusively and it’s excellent.