Having Origin enabled in-game has always caused issues on Macs. As well as causing lagging issues it can also cause your game to not load, something which seems to be becoming more frequent amongst players. So the best thing to do is just disable it. Unfortunately you will have to do this after each Origin update as it annoyingly enables itself each time.
- Open Origin then click on Origin > Preferences in the menu bar
- Click on Origin in-game on the right side
- If Origin is enabled in-game the button will show green. Click on it to turn it off so it looks like the picture above.
The wonderful Sims 4 Studio people have released the latest version for Mac and it supports object recolours!! I am beyond happy right now, no more having to move between Windows and Mac. We can’t yet edit and create meshes but being able to recolour is a massive step forward. It’s still a beta version so may be a little buggy but it does support macOS High Sierra – recolour away!
Here’s a link to using the Sims 4 Tray Importer in macOS. Getting it to run seems a bit hit or miss but it appears that with a little perseverance some users are getting it to run in Sierra.
Sims 4 Tray Importer for Mac
The guide is really detailed and very easy to follow and the comments are very informative too – good luck!
Update January 2018
As of January 2018 the Mac version of Tray Importer is no longer compatible with the Sims 4:
S4TI for MAC is no longer available. The app no longer works with the latest update of the Sims 4 and the developer does not want to provide support on MAC (platform it does not have and which greatly complicates its development …)
Sorry folks, seems like it’s the end of the road for us Mac users. I’ll update this page if it is resurrected.