Adding objects to far files can make a substantial difference in game load times. This is due to the way the game loads the files. If you have not read my Cause and Effect Article you should do so to get a better understanding of what causes long load times and the effect using FAR files can have.

Warning: You should make a backup of your user created objects prior to using this or any other tool to edit them. This is not automatic with SE Object Manager due to the number of downloads and file sizes involved. In some cases this would require several hundred megs of space. User created objects are usually located in the Downloads folder and\or the GameData\UserObjects folder which are both under the Main Game directory. (C:\Program File\The Sims in most cases)

First some Basics.

1. Putting your *.iff objects into many small far files will not have a very big impact. In fact it may not have any if you make one far per object.
2. To have the greatest impact you need to put as many *.iff files as possible into each *.far file. I suggest limiting the size of each one to the amount you can fit on a CD. (About 650 MB)
3. How big can they be? There appears to be a 2 Gig limit in the game itself. Theoretically it should be 4 Gig.
4. To have the most impact you need to place all object iff files in fars. These will be the ones in your Downloads and/or Gamedata\UserObjects folders. Just having a couple of object iff files can increase load times substantially if you are using Windows XP.
5. Will placing the objects into far files mean I have to start over and buy everything again? No, As long as you put the far file into the Downloads or Gamedata\UserObjects folder it should still work just like before. The game uses the Object GUID to determine where it is used in the game.
6. Do I need to remove the iff files that I put in fars? Yes, If they are left then the game will load them instead of the far embedded object.
7. Are all iff files objects? No. There are a lot of game files that are not. Basically iff files found in Downloads or Gamedata\UserObjects folder are usually object iff files.
8. Can object iff files be anywhere else? Yes, but it is not common or likely that you will find them elsewhere. There will be other *.iff files used by the game elsewhere though.

To outline what needs to be done:

1. Move all *.iff object files to a folder that is not located in the game.
2. Create *.far files from them. (I suggest 600 MB as a maximum size, there is a 2 Gig limit)
3. Put the far files containing the embedded objects back into the game.

Step by Step:
(This assumes you have a basic knowledge of Windows and working with directories and files.)

1. Find a good storage location that is not in the game path and create a new directory called SimObjects. (The name is not important but do not give it the same name as any other far file in the game) This will be a storage location where you can wok with your iff files to sort them etc. and will be the parent folder when creating your far file. (Note: TMOG will not recognize objects in this path so you will need to copy the iff back or clone it from the new far file to work with it using TMOG)
2. Now this part will take a little work. You need to go to your Downloads and Gamedata\UserObjects folders and move all of your iff object files from them over to the new folder. I suggest you maintain the original folder structure when doing this. (It will not matter if they are in sub directories or not) Especially if you have your objects sorted out into separate directories already. Note: There may be other types of files in these directories. If so then do not move them from the original location. For instance there are several far files in different directories under downloads installed by various expansion packs. You might also find some with an extension of *.hot or *.hit or several others. If so then leave them there. They may be needed for some particular object to work properly. Off hand I think the Sims Plus Arcade Games are like this.
3. Once this is done you have a decision to make. You can either sort your objects by categories and save them to remove extra garbage from them or just make your far files. Once they are in a far file you will still be able to categorize them with the SimEnhancer Object Manager but you will not be able to change the name, description, correct missing thumbnails, or clean the extra garbage from them left by other programs (Automatically performed each time an iff is saved with the SimEnhancer Object Manager). All of these require the length of the file to change which in turn requires a new far file to be created which is not practical.
4. Now you need to break up the objects into separate directories if their total size is greater than about 600 MB. (Suggested size) You can check the size by right clicking the SimObjects directory (Or Whatever you called it) and choose properties. If it says the total size is greater than about 600 MB then create a new directory called SimObjects02. Again the name is not important but do not make it the same as an existing far file in the game. Then move part of the objects from the first directory into the new one. Keep doing this by adding directories and moving objects until all of them are around 600 MB. Note: This may not be necessary and you can use your own judgment regarding how you divide things up. Just remember there is a 2 Gig limit for far file sizes which are directly related to the size of the objects plus enough for the index.
5. Now you should have all of your iff objects removed from the game path and they should be in one or more directories where you can manage them. Now open up SimEnhancer Object Manager and click the Folder to Far button. (Note: there is an option to include path information in the far file. This add a relative path to each file based on the directory structure under the SimObjects Folder, I suggest that you do not use this since it will increase load times)
6. Browse to the SimObjects folder and select it. Then click OK. When the SimEnhancer Object Manager finishes creating the new far file a message will pop up. Do this for each parent folder you created.
7. Now using windows explorer locate the new SimObjects.far file. (It will be the same name as the folder you selected which may be different) This will be at the same level as the SimObjects folder. Not inside it. Put this into your Downloads or Gamedata\UserObjects folder for the game. If you created more than one then place each one into the game.
8. That's it. Run the game and your objects should still be there but the game should start faster now. If you need to manage your objects then you can either work with the iff objects and create new far files each time or you can work directly with the new far files using the SE Object Manager.

Note: I am using one large far file that contains about 1800 User Created objects. The far file is just under 600 MB. The result is that my game loads in about one minute now instead of 10 to 20 minutes.