And the repeating script errors are coming back...

Oh, I didn't notice both Age and Grow on the list of the OP's mods (I have Age but not Grow, am afraid both would be too much for my overstuffed worlds). I also have to question the need for Buzzler's Aging Manager if you are already using SP. And I do run SP progression on Slow or Snail most of the time.
NRaas > SP > General Options > Adjust Speed

I also don't really know how much, if any, overhead Awesome adds to the mix as I let that one go years ago. I take it you are running SP's progression though, and not Awesome's StoryMode? Awesome's can be much heavier as it makes things happen on screen that SP would otherwise make happen by way of stories and effects.

My processor is a little faster than yours, but your graphics card is a bit stronger than mine; I would expect our systems to be able to handle around the same load but of course we all add different variables to the mix with our mods and styles of play. It certainly does sound like your ongoing game is more stressed out than is healthy for it right now and relieving some of the sources of that stress, once you get the schools thing squared away, might help put things back in order.

Or, possibly in addition, you have or had a mod concerning Service Sims that we cannot see that is having some kind of impact that we cannot determine. Sorry to keep coming back to this point, but this is why I suggested some test games off to the side with and without all of the non-NRaas mods to see if the stress is in your ongoing game only.

Okay, I don't know what service sims mod you're talking about, but I checked and disabled the Awesome StoryMode. Unfortunately, the script errors keep coming up every second.

I'm sorry, I know this is going to sound cranky, but you are only reacting to about 1/2 of the things I have been saying and ignoring the rest.

I don't know what Service Sim mod I'm talking about either. We have no way of knowing what mods you may have or have not had in play at any point in this ongoing game's history. All we know thus far is that this ongoing game is being affected by some breakage to do with Service Sims that our other players here do not experience, and it's not entirely hardware related.

I understand that you cannot simply yank AwesomeMod out of play entirely with an ongoing game, there is a removal procedure to go through first. I believe this is true for each of Consort's Grow and Age as well. But, and this will be the third (and final) time I will ask this. If you start a new game off to the side with either your current set of mods in place or NRaas only, does it perform properly?

If this were my ongoing game, one that I did not want to abandon, and if newly created ones test out well for performance and without the script errors, I would be making plans to get my sims out and into a different world one way or another.

Ok, I started a new game with my mod list unchanged (but I did get rid of Age and Grow before I did, btw, as well as Buzzler's Aging Manager), and there seems to be no script errors. But I don't want to have to move my legacy family

We'll have to wait for Chain to return to this thread to see if he suggests anything else.

But from what you have described, your NRaas mods are working well (in another game). It is possible, for reasons that we haven't been able to determine from just that one script log, that your ongoing one is not really going to be serviceable.

Okay, I'm playing the ongoing game again and there are no script errors... buuut, my sims still go to the original crowded school...

And the game is lagging like heck again. This game doesn't want me to play it, does it?

What's worse is my school sims are doing the taking turns thing with the school, and letting other sims cut in front of them and go into the doors.

The lag is actually getting even worse now.