Some people have issues with saved games not showing up in the save game chooser screen when they have too many saves in the Save folder. Over 50 is commonly when people have trouble, but some can go much higher. I'm surprised you aren't having trouble with 199 save folders. Moving or deleting some of those saves may avoid issues with the save game chooser screen, but it won't affect game play. I don't know if it would affect EC 12. If you don't have much free space on your hard drive then moving those save folders could be helpful.
Your DCBackup folder houses CC files which (AFAIK) are used to include CC in lots which you export and upload to the Exchange. It's also where your ccmerged.package file lives which holds resources critical for Store premium objects. If you don't have any Store content then you probably don't have a ccmerged.package file so moving the folder shouldn't be a problem. I think the game will recreate it if it needs to. But if you do have a ccmerged.package file there you should replace the folder. You can delete or move the other files in that folder if you want, but I don't think that's going to do much for EC 12 or game performance.
EC 12 occurs when the game runs out of resources (including but not limited to RAM). I've run into EC 12 quite a bit over the years and sometimes I just have to abandon a save. Sometimes though I can work around it. Here are some suggestions that have worked for me in my current game which has been plagued with EC 12 for the past few months:
1. If you are playing with a large overstuffed household (over 20 sims) try playing with less sims.
2. Move the household to a smaller and/or less populated world.
3. In the game's graphics options panel reduce Texture Detail to Medium (if you have it currently set to High). This has made a big difference in my current game.
4. Regularly save, quit to desktop, and relaunch to continue playing. In my current save I do this once a sim day (at night).
5. Monitor RAM usage with Task Manager (if you play on Windows). If RAM usage gets much above 3.0 GB it's time to save, quit to desktop, and relaunch. I also monitor 'commit size' in the Task Manager's Detail tab (you have to add that column manually). I find this is a better predictor of when I'm at risk of running into EC 12. Once the 'commit size' (which I think has to do with RAM requested but not necessarily used by the game) gets much above 3.0 GB then I save ASAP, quit to desktop, and relaunch the game to continue playing.
Once you do get EC 12 you can try a few things to get the game to save:
1. Go into map view which reduces the RAM the game uses, wait a few seconds for RAM usage to settle down, and try to save.
2. Point the camera to a bland patch of ground in the world (so the game has almost nothing to render) and try to save.
Both of those methods occasionally will work for me. But more often they fail and either I'll get repeated EC 12 messages or the game will crash. If they do work then I quit to desktop and relaunch the game to continue playing.
To keep my game 'clean and healthy' I use NRaas Overwatch, ErrorTrap, and I reset everything in town every 2-4 sim weeks with MasterController. I'm not sure any of that will help EC 12 though.