You're the person I'd happily waste time with.
sei la per-SO-na con KWI mi pia-ce-REBbe per-de-re il TEM-po — stress on 'so-', 'kwi', 'reb-', 'tem-'.
A sophisticated and slightly paradoxical flirt — 'losing time' with someone is actually the most pleasurable form of time spent.
'Con cui mi piacerebbe perdere il tempo' = with whom I would like to lose/waste time. 'Mi piacerebbe' = I would like (conditional of 'piacere'). 'Perdere il tempo' = to waste/lose time. In Italian, losing time with someone you enjoy is not truly wasted — this ambivalence is the beauty of the phrase.
Con te, il tempo non esiste.
With you, time doesn't exist.
Time disappears in their company — the highest compliment
Non ho mai visto il tempo passare così in fretta.
I've never seen time pass so quickly.
Specific to this encounter — the speed of enjoyable time
Potrei restare qui con te per sempre.
I could stay here with you forever.
Bold and beautiful — 'per sempre' is a big Italian promise
Italians have a complex relationship with time — the concept of 'dolce far niente' (the sweetness of doing nothing) celebrates the pleasure of unhurried time. Choosing to spend time with someone — even if nothing productive happens — is a very Italian form of appreciation and affection.