Docs pages are taking long time to load

[yurishkuro]

I noticed that the docs pages are freezing while loading, the top menus are not accessible until the page unfreezes. It seems the cuprit is loading of index.json that contains the index to support the search bar. This file is now at 3.4Mb.

• could it be served in a compressed form?
• does it need to be this large? it's possible that it indexes all versions of the docs, we probably don't want to do that

[yurishkuro]

Also, why does loading of this file block the UI? It should be loading in the background.