FIX FOR SEVERE LAG

Just to be sure I understand this right. You're saying the ingame clock does not move but is stuck at a certain time and the Sim doesn't move anymore either ? All of them ?

No. That is not right. The clock continues to run just fine. The sims are stuck in ultra ultra slow motion as it relates to the clock. Take the action of sitting in a chair. That might take 5-10 seconds of sim clock time. If you have this bug it might take your sim an hour of clock time just to sit down.

Does it get stuck at a certain time or is it more an stop and go ?

The clock doesn't get stuck though it can appear to be stuck. You might see it appears paused but then all of a sudden the clock self corrects by 2 sim hours.

To see if this is a reproducible issue, it would be best if someone could send me a savegame as soon as I get ITF (which with my luck will take another week).

I could send you one of my games that is messed up but I have an awful lot of EA store content in my games. I am trying to reproduce this with no mods. This happened on my Midnight Hollow game that I was playing before I installed this expansion. I pulled Twallan's mods before I played it but I had been playing the game with MC and OW prior to installing the expansion. If I reproduce with a mod-free game I will definitely re-post. Other simmers who do not have mods are telling me they have the same problems.