
Tenya Iida is not slow, a lot of his competition are simply working with so much more than him.
"Tenyas whole thing is speed yet he's not even top 10 in the verse." I know it's more of a joke than anything but I'd like to point out how this simply is not a fair statement.
All Might: Has a quirk built upon the efforts of 7 other people training it for a decades
Deku: Has a quirk built upon the efforts of 8 other people training it for over a century, plus extra quirks to further stack even more speed, even with a dedicated "simply go faster" quirk.
Star and Stripe: "I'm simply fast now, lmao."
All Nomu: Bioengineered super beings.
Shigaraki: Hyper-modified super being with dozens of quirks to further stack for speed.
All for One: Dozens of quirks to stack for speed.
Dark Might: External power booster for most of the film.
Nine: Yet another copy of All for One, multiple quirks to stack, also on drugs at his peak.
Like out of all of UA, the only other characters to reach super high speed with one quirk are Nejire, who's in the Top 3 of the school, and Bakugo who went through 2 quirk awakenings to get to that point.
Then the rest of his single quirk competition are the No. 1, No. 2 and No. 5 heroes and Gran Torino.
Of course he slower than the literal top heroes of the entire country of thousands of Pros, or the many characters with multiple quirks and bioengineered bodies.
For someone in only their first year of high school, working with just one quirk, Iida is amazing.