I've been using MCCC for four years to slow time, and I haven't noticed my Sims taking any longer to finish tasks. They cook, eat, bathe/shower, walk, and work on their computers just fine. Some of my Sims are pro gamers and their tournaments don't take any longer than what is normal. All the tasks associated with careers don't require any extra time as far as I can tell. But perhaps that is because after four years I just don't notice it. I do notice that little bit of extra time (I have MCCC set to it's lowest setting for slowing time) when there is a toddler in the home. I seem to have a lot of extra time to make sure the toddler builds their skills than I did before. The only thing I have noticed, is my Sims seem to get tired earlier at night. And I am not ashamed to admit I will use the UICheats Extension to give them a bit more energy so they will go to bed at midnight or so. The only way to know if you will like using MCCC is to try it out. If you don't like it you can just delete MCCC from your mods folder, and go back to the way you were playing. Just be sure to delete the Thumbnailache before you restart your game.