TM Cache mechanism details implemented with WS11.6

I read the release notes of WorldServer 11.6 and realized that the TM Cache mechanism has been implemented with it. I'd like to understand well regarding this new feature. 

https://docs.sdl.com/770288/789617/sdl-worldserver-11-6-user-documentation/release-notes/translation%2520memory%2520lookup%2520improvements

We are using 'Live TM mode' for our translation workflow. However, according to the explanation in the release note above, if we introduce the TM Cache mechanism, which is a default setting, it becomes NOT Live TM mode. I'm very confused. Could you explain the relation between 'Live TM mode' and 'TM Cache' mechanism?

Kind regards,

Naoki