I tried making a game with just the base game, Seasons, OFB, and Freetime, and even with max settings, it ran much better than the full game with default settings. But I would like to see what else I can install without there being much more lag, because I really enjoy my game like this (looks really nice, and loads really fast, and no freeze ups except sometimes during max speed) but still, it could get a bit boring with 5 EPs and all SPs missing.

Also, which EP allows me to view wants and needs at the same time? It's annoying having to switch back and forth.

Well, Bon Voyage is quite laggy on my computer, especially when my sims are on vacation. It might just be my computer though. (It's ancient.)

You must be in windowed mode. In fullscreen, for me at least, I can see both needs and wants at the same time, but not in windowed. For some strange reason.

Do any of the SPs add any noticeable lag? And I've noticed that AL seems to add a LOT of lag.

BV is laggy to me and I have a fairly decent computer.
Houses don't lag though, only community lots.
I have this with all community lots. :s

I've done some research, and I found out that AL is the laggiest, followed by BV, then FT.

Oddly enough, the three newest, if you look at it.
Way to support older computers, EA.

It depends on your computer because I noticed virtually no lag over the years while I added Eps and Sps. The sims 3 however...

Before I updated my graphics card, whenever there was water around (sea, ponds, rain) my game was laggy. I thought that AL, Seasons and BV had the highest requirements and therefore would be most laggy.

For me its trees! If there are more than 1 or 2 trees on the lot my game is soooo slow. I never put trees in my lots because of it lol

There is a hack that if you do put trees on the lot, you can at least "hide" them from view while you're playing the lot.

Although it doesn't make any rational sense besides for the "pretty points" for the sims to have trees on the lot.

Because they do cause major lag in the game-the more of them, the more lag.

I think it's your resolution that affects that, and in my experience that changes based on the amount of EPs your computer can handle.

Like, on my old computer I had up to OFB with the Holiday and Family Fun Stuff packs running on med settings and it was fine. But when I got Seasons/Pets the resolution screen went down to 800x600 (I installed the two 12 hrs apart, but the resolution shrank when I added Seasons first) and I had to turn more settings down to low/med. That's when the lag started too.

However, on my current computer I have Base, NL, Uni, Seas, FT, BV, and AL and 1 stuff pack. The game still runs at large resolution and I can see both the wants/needs tabs, as well as run the game with high and med settings (med being my preference, not required) with brief lag only when Witches fall from the sky and when I have a huge wedding party.

The difference? My current laptop is on the higher-end, with a better card, more space, and more ram compared to my old one. So I think it depends on your computer.

Wait - some people can't see wants and needs at the same time? How? Like, you can't have both panels open? Only one or the other?

Keep in mind that games that are graphic-intensive and drive-intensive are things to consider when looking at computer specs. TS2 accesses all those files in the TS2 folder frequently, so you will get a performance hit if you have a slow hard drive. A lot of laptop computers have 5400 rpm or slower hard drives because of the heat factor. But often you can put in a 7200 rpm drive at little cost.

It used to be that desktop computers always had fast hard drives, if you bought a name brand, but many companies cut corners wherever they can, especially when consumers don't know about the specs. You can get a 10,000 rpm hard drive, but they are premium and won't be cheap. Graphic cards, processor, hard drives and RAM will all play a part in your game performance. If your game is really important, then you have to pay to get better specs. Better specs means you can usually still use the same computer when the next latest and greatest comes out - TS4 or something. But also pay attention to your monitor. The best graphic card won't do any good if you have a crappy monitor.

I got my computer so that it was more than the minimum requirements for TS2, though I didn't buy it specifically for this game. I made sure I got as much RAM, fast hard drives, and graphic card abilities as I could afford. But I added the extra hard-drive space and RAM after purchase so I wouldn't have to wait longer to buy the computer and they were cheaper doing the install myself. It will run TS3 comfortably I hear but I'm not interested in upgrading because there are still a lot of things I haven't done in TS2 and I am definitely having a lot of fun and not getting much lag.

There are hacks that will diminish the weather effects of Seasons so your computer won't have as much lag. I like all the rain and drizzle and gray skies but sometimes it does give me a headache. I have ponds on every one of my lots, small lots, big lots, community lots and Uni lots. Even my downtown lots have ponds, though I think a few don't because I haven't gotten around to recreating them. I love the fishing so I've been getting rid of all the lots that don't have room for a pond of a decent size.

I haven't noticed that trees slow down my game at all. All of my lots have several trees, mostly orchard trees, but I can't think of a lot that doesn't have at least a half-dozen other trees along with the fruit trees. But I use mostly medium and large lots so I can place the trees a few tiles away from the house to see better. And smaller trees, shrubs and flowers by the house. My fortune sims complain the most if I don't have enough trees. As much as I love nature and gardening, I don't love lots heavily filled with trees because I have to keep moving around to see. So I am always on the lookout for small trees I can download to satisfy my sims' wants for trees.

I recently bought some more RAM (the maximum amount for my computer) and that has made a world of difference!
I'm looking forward to getting Seasons sometime just to see what goodies it holds. I can now play all my lots with the trees and extras enabled.
So if the OP wants better performance, the way to go is to get as much bang for the buck in the computer to have as little lag as possible.
BTW, it helps to keep your computer in tip-top shape by performing chores such as defrag and cleaning out extra/unnecessary files from time to time.

Yeah, when you click one, the other closes. It's very annoying, but you get used to it.

I have a brand new HP computer with 6GB of RAM, a NVIDIA GeForce 9600 GT graphics card, and not many programs installed on there... basically, nothing except Sims 2, and that's the way it's been since July.

However, I've found Bon Voyage and Apartment Life do add a lot of lag. I'm pretty sure with BV, it's due to the water and hammock. AL, too many people on one lot. Same with Seasons; the weather makes my screen lag more than ever, and a few people have complained graphics requirements for that expansion are too high.

Funnily enough, I found University, Open for Business, and Free Time had generated the least lag.

Glamour Life also seemed to give my computer some issues.

Well on my computer this is how much GB each expansion pack takes up:

The Sims 2 - 2.74GB
Nightlife - 1.25GB
OFB - 697MB
Pets - 801MB
Uni - 925MB
AL - 1.21GB
BV - 946MB
Seasons - 869MB

I haven't got FreeTime so don't know how much space that takes, but I'd say the ones that cause most lag are AL and Nightlife.