Feat here. Happens in Action Comics Vol 1 642. Hal causes time to freeze to "a fraction of a nanosecond", and of course, he, Superman, and Deadman are completely fine.
For "a fraction", I'll assume 1/4th.
For observer velocity, I'll use 1.7 m/s. Using any higher speed doesnt seem to change the results a whole lot until I get t unreasonable numbers. Putting that in a calculator yields 2.5e-10s reactions, so FTL.
Another method. Ill assume they were walked 1.7 m/s in 1/4ns
1.7 meters / 0.25 nanoseconds = 6,800,000,000 m/s (22.6c)
Now for attack speed.
Hal was in an unspecified but highly desert-ed place in Northern Utah, and shot a beat to Cape Town in 1 nanosecond.
According to Daftlogic, that is a distance of 15,775.5 km
15775.5 km / 1 nanoesecond = 1.57755 × 10^16 m/s (52,621,403.8c)