I have added ACR 2.0 on its own with no other mods and it causes poor game performance. I have used mod without ACR and game performance has been fine.
I have researched but there was nothing relevant.
I have no idea why ACR would be causing poor performance other than it is doing a lot in game that I don't know about.

Your issue sounds like the reason why I played TS2 vanilla on my oldest laptop which wasn't really designed for games.I would've had performance issues on that old computer if I tried using CC and hacks.It didn't have a dedicated graphics card and was a slow computer with Windows xp.My current one uses Windows 7 and has a dedicated graphics card and I'm playing with an insane heavy load of CC and hacks on this computer and my game still runs awfully fast.It's also an older computer from 2012 and it still runs almost like new.

It is running fine right now, but not vanilla smoothness but its definitely an upgrade to what I had before, especially since this is a big lot it's running smoothly on.

Well, what do you mean by "poor game performance?" It could be that you're using an older computer that can't handle custom content well at all, it could be that you need to do the texture memory fix, or change your graphics rules. In either case, it's kind of hard to help you if no one knows the specific problem you're trying to solve. Is it just lag? Are you getting purple flashing?

Otherwise, I can just point you to the generic help faqs/steps. Start with the ones stickied at the top of this help forum. Especially the one about Windows 8. Make sure you've updated your Graphics Rules. Also do the CFF Explorer Tutorial. Remember that keeping your game on for long periods of time can also cause lag and problems; it's better to actually shut down the game and restart every few hours, rather than keeping it on for days. ...Without more info, that's all I got.

Considering the slow processor and next to nothing ram, it's not surprising that you have lag when adding anything.  Windows will use half of your ram, so be sure to close every other program when running sims.  Even disabling the internet and your AV would help.  Uninstalling some of the later EPs would also help it run smoother.