Lol no.
when you're building a complex nominal with case endings and possessive endings and what not, do you think of them as kind of separate words as you're speaking?
No.
break down the pieces mentally
No.
do you start a word without yet knowing what particles and endings will be attached
No.
finnish endings are completely intuitive, it's just a different paradigm
Yes.
I'd indeed advise you to ask r/linguists. I am one, but this isn't my field. Pauses and hesitation are normal in any language, and have many different reasons. I have no idea how the number of pauses between synthetic and analytic languages differs, but I assure you, no native speaker builds vocabulary items in their head like building blocks.