Translation:You are slow, just like a turtle.
I find it difficult to distinguish between the two at normal speed -- if you listen at low speed it should be easier to distinguish between jij ("yay") and je ("yuh").
They both mean "you", but "je" is the normal, un-emphasised form of the word... "je bent langzaam" is "you are slow", while "jij bent langzaam" is "YOU are slow".
The two options available in my case were "net" and "zoals"... by logic I could infer that selecting "net" had a higher chance of being the right word, since "zoals" was right after it.
"He bent langzaam, zoals zoals een schildpad" even without knowing really well the meaning of the word and given the multiple options, it is perhaps a little bit too easy to figure this question out, without really knowing what is going on. Nevertheless it might be just my opinion. :)
As well as means and also/and in addition, so if you use that here you are saying that someone is slow and also a turtle, instead of just like a turtle.