Hi Kimberly,
I just did a small Render test and the same scene that took about 16 seconds on my desktop with RTX4090, took about 4 minutes and 40 seconds on my Laptop with RTX4090.
Maybe I somehow got a ‘broken’ Laptop, but I really wouldn’t expect too much. And as @Littlesheep mentions, make sure you somehow test any Laptop you buy.