Excessive Loading Time (several minutes)

Do you have any mods or CC (custom content)? Try taking that out.
See this for more information: [PLEASE READ] Usage of Mods and Custom Content

I did have CC and it was on my computer when I installed the game, but I have taken it out since. Did installing when I already had CC mess my game up? Should I reinstall?

Not sure, do you have a The Sims 4 folder the Electronic Arts in your Documents folder? Try renaming that and see how the game responds to that.

Yes, I have a folder called Electronic Arts that's in documents and there's a folder labelled The Sims 4 inside that.

Try renaming that The Sims 4 folder and test the game.

I'm confused, what should I relabel? 

The folder of The Sims 4. Change to 'The Sims 4 back up' or whatever. It's just to test.

Ok, what I did is I uninstalled the game, renamed the old The Sims 4 folder, and then reinstalled. This solution seemed to work! I guess when I installed while I had the Sims 4 folder on my computer (I had entire hard drive transferred onto this laptop) that messed something up. My original download times (I installed it twice) for the Sims 4 base game, all 3 expansions, 5 game packs & 5 stuff packs were less than an hour... last night the base game alone took more than an hour. So that should have been a red flag. Things seem up to speed now though. Many thanks!

Ugh, actually it only loaded quickly the first time after reinstalling the game. It's loading quicker than it did the first time around, but still not the ~15 seconds it was on my old machine. I am super frustrated with this. I just want to know if it's something I did, if there is something wrong with the game or if it's my computer's fault somehow.