glitches and ram

jtk0291  If Sims 4 is using 8 GB RAM but your system is using 95% of its installed memory, then the problem is not really the game but rather everything else you're running alongside it.  How much memory is in use five minutes after you restart the system, with nothing running except the Task Manager?  Please test and let me know.

Adding more packs doesn't always increase Sims 4's memory use.  It depends on which pack, for example most stuff packs have no discernible effect on RAM use, and Get to Work has a much smaller impact than Cats & Dogs.  But I would guess most of the impact you're seeing is from your mods, unless you happen to have a single save you've played for hundreds of hours.  It takes a long time for the game to use that much RAM under normal circumstances.

For the in-game issues, please let me know what happens with no mods or custom content present, as in, move the Mods folder to the desktop and delete localthumbcache.package.  You don't need to save your progress, and probably don't want to given all the missing objects, but it's important to separate out the effects of mods and cc from anything else that might be happening.  Please also let me know how much memory Sims 4 uses with the Mods folder removed.