[XB1] Getting "Lag" on Sims executing tasks in a large household

Product: The Sims 4
Platform:Microsoft XBOX One
Which language are you playing the game in? English
How often does the bug occur? Every time (100%)
What expansions, game packs, and stuff packs do you have installed? City Living Vampires Vintage Glamour stuff Dine Out Romantic Garden Stuff Cool Kitchen Stuff Awesome Animal Hats Digital Content Life of the Party Digital Content Up All Night Digital Content Perfect Patio Stuff (Basically all content currently out for Xbox as off 2/23/2018)
Steps: How can we find the bug ourselves? Unfortunately there are no specific steps other than what I think is causing the issue. 1. Have a house on a large lot 2. Fill that house with 8 sims (currently 1 Elder, 2 Adults, 3 Young Adults, 1 Child, 1 Toddler) 3. I have built on the lot a large house with 2 above ground levels and one basement. 4. I have filled the house with many items, both decorative and crafted. I have many paintings. I had many more, but as a test to see if it helped, I have reduced down to say 20 paintings currently. 5. Play the game for many sessions/hours.
What happens when the bug occurs? Over time, the game will start to exhibit that I call lag. Each Sim, when they go to do a task will take a long time to 1) have that task drop down into the "execute" slot and 2) when that does occur, it takes some time to actually do the thing. The game itself is not hung or locked up, and in fact time continues to progress, or if say someone was playing an instrument or going to the bathroom, then will continue to do so over the course of many minutes or sometimes up to an hour of game time. How that manifests for me is that every action basically pauses for about 10-15 seconds, then they will do the next thing. So it is like this... 1. I add to a Sims queue: Go to the bathroom, take a shower, eat a quick meal 2. It will take 5-15 seconds before the bathroom command drops down to the execute slot (time is still moving on the clock) 3. Maybe there is another lag then they walk to the bathroom and sit and pee. This will hang again, while time progresses. 4. the same basically then happens for standing up, flushing, washing hands, getting in the shower, showering, getting out of the shower, walking to the fridge, getting the food, sitting, eating, standing, grabbing the dish, and then washing. Over the course of all those actions, which should take maybe 3-5 minutes in real time, takes 15-20 minutes. And in game time it is 3 hours. If I pause the game at the spots where it lags and wait the 20ish seconds, then game time stops moving (of course), but it feels like the game itself is "catching up" on its tasks. For example, if it is morning and then notices for royalties shows up, that will lag things, but eventually it pops, then when I unpause my sims proceed to the next task until something else causes them to lag. The things that tend to cause it to lag are: 1. Someone waking up in the morning while another sim is doing their tasks, especially if many of the sims wake up at the same time (big lag spike). 2. Notifications...any of the,. Bills, skill ups, royalties, going to and coming home from work/school. festivals. 3. Chatting....Getting sims into complex conversations seems to cause them to lag, they just stare at each other for like 20 seconds, then do the next chat item, stare, then next chat, etc
What do you expect to see? I expect the game to run without these lag hitches, up to and including large households. I expect some movement lag in a house with a lot of items, but this is not that time of lag, it is actual procedural lag where they stop executing tasks for some length of time before the game catches up and lets them do it.
Have you installed any customization with the game, e.g. Custom Content or Mods? On console - never used.
Did this issue appear after a specific patch or change you made to your system? No

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As an additional bit of information. I have tried clearing the Xbox cache, which you can really only do by powering off and waiting some time before plugging in and booting, but that didn't help at all.

What DID help is odd...

I tend to play with my games on external HD's, but to just try something different, I moved it to the internal drive. For a time, this made things significantly better. Still not perfect, but playable. However, over time and play sessions the lag came back, and so today I moved all the game content back to the external...and it is now playing "better" again.

So I am not sure if there is some caching issues somewhere, where cruft is building up over time and causing the game to bog down, but I offer this info in the hopes it will help.

Overall, this lag does make it really hard to play the game, unless I am in a small household with few sims.