The CY2309 with PLL enabled has very little propagation delay if all outputs are loaded evenly. The datasheet spec reads t6a < +/-350 ps. In bypass mode, the CY2309 bypasses the PLL and therefore acts as a normal buffer, with propagation delay (t6b) in the datasheet as
Min = 1 ns,
Typ = 5 ns,
Max = 8.7 ns.
With the PLL enabled, the part acts as a "zero delay buffer." In this mode, the PLL reduces the propagation delay from input to output compared to the bypass mode.