It's not the folder that must stay under 200MB (which is 204,800kb). But, it is each individual .ebc file within the dccache folder that needs to stay under that limit. More than that in a file means that some of the items in the file won't show up as options in your game. For instance, have you ever searched over and over for one special piece of deco, but it just could not be found? If yes, then you have too many items in the .ebc file that contains that item, and the item you were searching for just couldn't show up. (The launcher works the same way. At some point, it just can not show you any more items. It's too full. You still have the items installed, but you can't find them in the launcher... and sometimes not in your game either.)
In an effort to help items load, you'll get duplicate files that show up in your dccache folder as .tmp files. The logic behind them is that maybe if your item didn't load the first time, it'll load a second time. That reasoning tends to make your game have to work much harder because it has to load more initially and save all the extra files.
The only way I know to prevent this... is to start at the beginning with a fresh install, which everyone hates, I know! I do too! But, once done, items won't randomly disappear on you. If you know how much an item costs and the category in which it is found, then it's there!
So, 9.3 gigabytes is the dccache folder size. Within that folder, you have many .ebc files and .dbc files. The .ebc files are store items. The .dbc files are for custom content.
If I were you, I'd rename your current sims 3 folder and let a new one spawn on reload of a fresh game. Then, install the files in a logical manner one .ebc file at a time and watch the size to stay under the 200MB or 204,800kb which is the file sizes displayed when you look at the files in the dccache folder. Every time you are close to reaching or going over 200MB, make a copy of that file (in case you go over when you install the next item). (That saves you from reinstalling everything in that file again.)
When one file gets large enough, move it to a safe location and install more. You'll always be installing into a file ending with zero. When you finish a file, the first stays at zero, but each consecutive file needs you to renumber the zero at the end to the next number in sequence. I have just over two dozen .ebc files. My cc goes into the mods folder. That makes it so much easier for me to keep a clean game running.
If I didn't explain this well, ask me more questions and I'll try to be more specific with my help.