Yes, this is expected and certainly not a good situation. You are simply running into the fact that Julia is recompiling your code every time you start it up. The plotting ecosystem involves a lot of code, so it tends to exhibit this issue more.
Try this: start Julia, copy in your code, wait for it to compile and run. Then, without closing Julia, run it again. You should see it run essentially instantly as you expected.
This will improve in future Julia versions, but for now I’d suggest modifying your workflow to do more in a single Julia session rather than restarting the Julia program frequently.