He doesn't use VS6 himself, he was most likely referring to Sean Barrett (aka "nothings") who worked on the original Thief as well as at RAD Game Tools and made the stb_ single header libraries. He has mentioned several times that he sticks with VC6 since he prefers the UX it has.

Yeah when he said this it I couldn't help but think of Sean Barrett/nothings.org coding videos. I was always shocked by people using VS6 post 2003 but it provides 50-75% of what people want from an ide these days. (A big proponent is inline debugging as mentioned) but I don't recall intellisense on this version, only keyword colouring and non trivial header exploration... Makes everything look bearable these days (even if run from a browser UI)

VS6 has intellisense but doesn't cope that well with macros.

VS 6 is great, honestly, if you're just hacking c89 or a narrow subset of c++98. Look out, though, the compiler isn't fully standards compliant.

VS6 was such a great product.

I tried out VS 2019 last year on a whim. The last time I used VS before that was in the early 2000s (probably 6.0).

It was a surprisingly bad experience - weirdly slow even on a high performance PC and so much clutter by default.

Tried out VS 2022 just now. First impressions are better.

2022 was the first VS in 64 bit, the increase in responsiveness was enough to make me switch back from rider

It's probably due to optimizations in high level code rather than the 32/64-bit aspect, but I'm just guessing. (To get that level of slowness you really have to fuck up at a higher level.)

VS seems to be a WPF app nowadays, so I assume the UI is written in C#.

Since Visual Studio 2010.

Obligatory Casey Muratori rant about modern Visual Studio, complete with Visual Studio 6 running in a VM: https://youtu.be/GC-0tCy4P1U

Since I just re-watched it: he ran it on a P4 from 2003.