Sometimes it's just old playfields playing slower. But yes, pinball has sped up considerably over the years. You didn't notice it back then because all the machines near it were the same speed.
Lots of EM's the difficulty comes because they're slightly 'floaty' - with a lower slope than modern-ish games. Some early solid state games are like this as well, most set them up steep which actually makes them slightly easier - no longer as much risk of side drains for instance. I can't stand the slowness though on that era.
EM's I'm ok with the way they play, it's more of a nudge skillset the earlier you go back IMO anyway.
My DC experiment with Fast Draw's flippers ending up with me snapping 3 or 4 drops since they are so close to the flippers so I changed it back.