Yeah, docs site is still Liquid 1.0.
In most general cases Liquid 1.0 will work the same as 2.0, but it’s quite different in that 1.0 kinda processed ‘upscope’ while 2.0 goes ‘downscope’ (well that’s how I think of it anyway).
In 1.0 we could pass Liquid variables ‘up’ from a page content area into the head of a template for example. Whereas 2.0 works more like BC did, where variables are passed ‘down’ from template to page - which is more practical I think, but there were cool advantages of it being the other way too.
There are surely many other technical differences in the implementation, but that’s the most prominent difference I think in terms of developing with it.
I’m not sure as yet in what cases 2.0 would be responsible for slower site speed though. I’ve only experienced gains by turning it on so far.