Sims in Slow Motion
Delete the Scott Family
Use the cheat DiscoverAllUnchartedIslands to make all islands visible. I'm aware that this takes away from the fun but it seems to help some.
Make sure you have no stuck sims in your town (use the cheat resetsim * to reset all sims in your town and put them to a safe location)
Use Overwatch and ErrorTrap (those are mods and you'll be using at your own risk. Not supported by EA. Just google to find)
Check for any aboandonned boats in your game and delete them by using testingcheatsenabled true and then shift-click on the boat and choose object-delete.
If you're playing Hobart's Hideout, be aware of this issue: Routing Issues in the Resort Hobart’s Hideout
General tips for lags: Lags & Intermittent Freezes