rtx 5060 getting lower fps than my old 1660 ti??

Did you DDU the old driver before swapping? That's the usual one. Other things, roughly in order of how often they're the cause: monitor cable plugged into the motherboard instead of the card, an older board on PCIe 3.0 (the 5060 only uses 8 lanes so it loses a little there, but nowhere near 1660 Ti levels), Resizable BAR off in the BIOS, and Windows on a power saver plan. Also look at the CPU. If it's the same chip that was paired with the 1660 Ti, some games are CPU-bound and the new card just sits there waiting.