Slow/hard cold start, no other symptoms

When car has sat for at least an hour, car takes five to eight seconds to start. Warm starts takes one second. With a cold start, if I turn the key to on and wait ten seconds, turn it off, then turn it back on wait a few seconds and start it, it starts right up same as a warm start.

Idle is perfectly stable, there is no check engine light or thrown codes, and car runs perfect other than this slow cold start.

I have checked for leaks (none and LTFT stable at 0), replaced FPR, cleaned MAF, and run a strong dose of (in gas) fuel system cleaner through, all with zero difference. Ideas would be appreciated! (HPFP? If it's HPFP, shouldn't it be throwing codes?)