I never speedrun a game in my whole life but I once beaten Mario Kart 7 in 50cc in one sitting but I'm a fan of speedrunning and beating games the quickest as possible. Because The Sims 4, like most The Sims games for computers, doesn't have an objective, although many people "speedrun" past Sims games with specific objectives like max all skills without cheats and have as much Simoleons. I have some ideas for speedrunning The Sims 4.

• Fastest time to age from baby to elder: Have seven birthday cakes since you don't need one to age babies to toddlers, age up the baby, help the toddler blow off candles and have the child blow off the candles of all the cakes until they become an elder.
• All skills speedrun: Note that EPs and GPs add more skills and make the process longer. Have your Sim master all skills without cheating or the wishing well from a SP.
• Fastest time to get a specific amount of Simoleons (10k, 100k 1m, etc.): Do actions that make you richer like playing guitar for tips and going to work. It is faster while doing it with many Sims in a household but no cheating!
• Fastest time to experience all emotions (you may exclude Fine and superlatives like Enraged are optional); Title says it all but don't cheat. However, the emotion potion rewards are allowed.

My boss tells me I need to work faster, so in Sims I work/play as slow I like.

Nah, it's not the wrong game for Supersim64DS, it's just the wrong platform for his idea. Not within our comfort zone, I'm afraid. From my impression MTS is where the storytellers and simulation/complexity fans hang out. The official forums I get the feeling houses the realism/real life favouring players. Speedrunning appeals more to the game-mechanics beating inclined players, though I wouldn't know where these dwell.