In Gurren Lagann episode 26, Super Galaxy Gurren Lagann unleashes missiles against a swarm of the Anti-Spiral's ships. These missiles were repeatedly stated to attack through all of space-time itself.
What's more impressive though is that appears the missiles did this in a planck instant.
This is from the same scene talking about the missiles, and various other translations confirm that this is an actual time-thing and not just some technobabble. Or dimensionbabble I guess.
So in-essence, in this scene SGGL attacks all of space-time, including the entirety of the universe, in a planck-instant.
I'll be stealing most of my method from this calc on another site as I can't think of any other way to go about this, and both scenes happen to use missiles.
Anyways, I counted about 120 missiles launched in the scene where SGGL fires them.
For the diameter, the Anti-Spiral's homeworld is clearly much, much bigger than ours. I'd imagine you could try and calc a proper diameter based on the size of the Super Giga Drill in the final fight in the movie, but for this calc I'll just lowball and assume a diameter of 10 times our universe's diameter (8800000000000000000000000000m for the AS's homeworld). That's about how big the Giga Drill is so I'm not pulling that out of nowhere.
Assuming a 20km or 20000m radius and calculating the missile's FOV as a cylinder, using the diameter as a height
Volume of FOV= 1.11×10^37 m^3
Then we need to calc the universe's volume as a sphere, as most calcs assume that's what it's shape is
Radius = 4400000000000000000000000000 m
Volume of universe = 3.57×10^83 m^3
Divide the volume of the universe by the FOV to get a proportion and the number of trips taken to cover everything
Number of trips taken = (3.57×10^83)/(1.11×10^37) = 3.216×10^46
Multiply that by the diameter to get a total distance crossed.
Total distance = 8800000000000000000000000000*(3.216×10^46) = 283008000000000000000000000000000000000000000000000000000000000000000000000m crossed total
Divide that by 120 for the distance covered by each missile, so 2358400000000000000000000000000000000000000000000000000000000000000000000 metres each
This was done in a planck instant, so 10^-43 seconds, so just divide the distance by that to get a speed for each missile.
Speed= 23584000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 m/s for each missile, or 7.8667756211532179371904012341764781821162425640474251... × 10^106 c, Massively FTL+ (should probably add a few more pluses). That's well over a googol times the speed of light.
Jesus. Yeah uhh, how seriously you wanna take this or if you wanna apply it to speed at all is up to you. I mainly did this for fun and cause someone I know showed it to me.