Improve throughput and performance under stress

Check out the related notes (with a link to the architecture group discussion on the topic):
https://www.notion.so/p4elkin/NYT-performance-problems-follow-up-80450e4ae4884520979707f0cc47677b

Customer feedback

From the product board (1, 2):

• Magnolia, Tobias Kerschbaum: "Multi-site performance — Dev5310, partner. Multi-site gets slow with languages. Multi-site; you have language availability through site config. How it works now: the Master has e.g. 20 languages, and when your LC only needs 2, it copies 20 languages but only shows the 2 (instead of copying the 2 only) // Norsu - partitioning on the table, have language on a different partition"
• Union Investment, Chris Chard: "The page editor is the no.1 in usability when it comes to the speed of building a website"
• Union Investment, Chris Chard: "Page reload after every edit (partially solved with the 6.2.29 release, they're on 6.2.27)
  Pages reload when you edit a component... and it takes a while. You don't know what it's doing, 
  and when the loading is completed... where is my component now? Does not stay in focus (this is fixed from 6.2.29)"
• VPRO, O Bruins: "the dynamic loading of pages is sloooow"