By lag, I mean whenever something got more than 1 territory, it took a second for every territory claimed (so if someone annexed a big nation, it'd take 3 minutes...).
I feel guilty for leaving a bad review when it was honestly my own fault. (The freezing was a separate issue that was fixed)

So what worked for me?
Deleting my old saves.
If you want to try it, it'll be under where Unity keeps putting game data on your computer.
For me it was
"Users\[YourName]\AppData\LocalLow\DefaultCompany\EarthRoyale"
Go under saves. If you save-scum like I do, trying to get your favorite country to win, chances are you've made ~20 saves or more...
Thin it down to around 5 saves, the lag should be gone.