A blog to calculate a pair of speed feats in Naruto, during the Invasion of Pain and its fight with Naruto Sage Mode passed some feats that is interesting to analyze, will be two first the speed of the Rasen Shuriken and then the speed of Deva Path when dodging Said attack, let's see:
Rasen Shuriken Speed[]
The Crater size of the Chibaku Tensei has already been previously calculated and accepted here and its size is 38780.9 meters; Rasen Shuriken toured this crater in a very small time, so I'll calculate the timeframe:
Tendou = 210px = 1,765 m
Arm (to the armpit) = 74px = 0,62 m
Arm = 105px = 0,62 m
Height = 312px = 1,84 m
Now the time it would take to Tendou in free fall, the official weight of Yahiko-Tendou is 57.2 kg
Time formula in free fall is https://wikimedia.org/api/rest_v1/media/math/render/svg/10f3d0383ea94ebc8fa369018069467481453818
Time = 0.61 s
Now, the time it takes for Rasen Shuriken to travel this distance is less than the time it took Tendou to fall to the ground, I'll assume he took 1/3 of that time so I'll use 0.203 seconds of timeframe (this can be debated):
Timeframe = 0.203 s
Distance = 38780.9 m
Speed = Distance / Time
Speed = 191038.91 m/s (Mach 561 - Massively Hipersonic)
That would be the speed of attack of Naruto with the FRS, by powerscaling this would also be Itachi's speed with Yasaka not Magatama and Killer B Bijudama (also of the other Bijuus) http://www.mangapanda.com/naruto/551/13. Also Sasuke's with his Enton Kagutsuchi http://www.mangapanda.com/naruto/632/19
Deva Path Speed[]
To calculate the distance between the Rasen Shuriken and Tendou as well as the time it would take to such attack to travel such distance:
Arm = 190px = 0.62 m
Distance = 65px = 0.21 m
Time = 0.21 m / 191038.91 m/s
Time = 0.00000109925 s
Now the distance that Tendou had to jump to avoid it:
Naruto Height = 178px = 1.66 m
Naruto Arm = 76px = 0.70 m
Naruto Arm = 124px= 0.70 m
Rasen Shuriken Height = 202px = 1.14 m
Then Tendou's speed to scrape the Rasen Shuriken would be:
Speed = 1.14/0.00000109925
Speed = 1037070.73 m/s (Mach 3047 - Massively Hipersonic+)
If this calculation turns out to be correct the characters of Naruto would have a severe upgrade. Thanks for reading.