I have an absurd amount of hours in EU4 and I have absolutely no lag in EU4 on my desktop. And I can think of at least two times where Paradox has had a patch that really significantly increased performance.
How often do you play past 1750? That’s when the 5 second month ticks happen for me. Also 2-3 seconds between clicks in the macro builder when you get 3000 provinces or so, methinks some algorithm is quadratic. Restarting the game helps.