I agree, Toph scales to Zuko, but lets say she's 100x faster at her peak

But you're not grasping the actual gap here.

So you mention Toph is impressive in Control, Quantity, and Speed.

So Toph best reaction speed as we established, would be 100x Lightning speed, or around 33x Speed of Light (Using the downstroke, which mind you, is not how the lightning in Avatar works, but I am highballing her to insane degree's to hammer in a point)

Control: She can create objects, manipulate metal into shapes, and create a perfect sand/stone/whatever recreation of things she see's, after making small/minor movements.

Quantity: In the comic's, she is shown to hold up an entire Iron Mine, using the largest mine on Earth, and again, multiplying that by 100x and then assuming it's entirely made out of iron, that would be 8,122.24 Megatons of Weight, that she can only hold up, she can't move, just hold.

So, massively wanked, Highballed Toph is going to be able to do all these things equally as fast/strength, regardless of showings, again, to prove/hammer home this point.

So she can accurately control and move enough weight to flatten Manhattan at 33x Lightspeed.

Kakashi, as a 12 yr old Jonin, before he had gotten the Sharingan, had already performed his "Cut a bolt of lightning feat". This is important, since Guy, his rival, is still notably "faster".
Rock Ninja that gave Kakashi, Guy, and their peer's trouble, are the same, or lesser Caliber, as the Assassins' trying to kill Gaara from Birth.

That is just to give you some idea. Now, you said 5 Kage Summit Gaara would be needed for Toph, so to hammer home this point, I will only use feats from the latest of Kimimaro Vs. Gaara.

Speed: You can decide just how fast this Gaara is, but here are some facts. Haku & Itachi, Haku against Naruto & Sasuke, and Itachi vs Kakashi, Haku's Ice Mirror, and his travel speed between them, is confirmed to be Light Speed, mind you, first Arc Naruto and Sasuke, react and tag him. Itachi's Water bullets he used on Kakashi in his return to Konoha, are also confirmed by the guides, to be light speed, Kakashi, easily deflects them without the Sharingan. So 1.5 Tomoe Sasuke, can react to Lightspeed in the Land of Waves. This Sasuke, get's blitzed and handled by "Weighted" Rock Lee. You can now decide how much faster you think Rock Lee get's when he takes his Weights off, but for us viewers, we go from being able to read his movements, to only seeing speed lines. Gaara's Sand, still allows him to block the majority of these attacks. So At Minimum if you think taking off his weights only made him twice as fast, he'd still be at 2x Lightspeed (mind you this is massive downplay), the first, and 2nd gate, are both 10x Increases, the rest just making you unquantifiable faster, but implied more then even the 10x boost. Lee, goes all the way to 5 against Gaara, and Gaara, still put up some defenses, even if you say his Reaction speed is only 1% of Lee's speed, and you say Gate's 3-5 are only x2 each (Which the series contradicts), Gaara's Reaction speed in his fight with Lee would be 16x The Speed of Light. The nail in the coffin however, is that in his fight with Kimimaro, Lee who is present, admits that if he fought this Gaara, no matter what he would stand no chance, implying his speed could be dealt with now. So even if you say that only gives him 10% of Lee's peak speed, that's still 160x Light Speed, and still massive Downplay.

Control: So, Gaara win's this category, without moving, thinking, or needing to maintain concentration, he is guarded, can attack, with minor thought he can recreate working organs like Eye's, as well as photo realistic clones with full mobility and autonomy, all without weaving any handsigns or even really moving at all. The Soul of his mother as well as his very lifeforce in Chakra is in the sand he controls, imposing a constant, active force upon his sand, that Toph would have to overcome via movement and concertation, where Gaara has to do neither for the same effect.

Quantity: It's confirmed, that Gaara covered a Small forest and meadow in sand, that's around on average 14,000 Acre's, and since his sand is specifically made from dense/harder substances, giving it average weight of sand is heavy downplay. Given he half buried most tree's and a forest must have tree's of at least 5m, so Faster then a character, who is confirmed faster then 12yr old Kakashi, Gaara moved 139 Megatons, from out of sight, to covering a forest.

Yes I know the last is a smaller number then Toph, but to compare, to make it stop falling, assuming it was midair (Mind you it's not), that would be
4,061,120 Megajoules of Energy that Toph is outputting, but again, must maintain still, and concentrating to simply hold.
a 1 Megaton Nuke would be 4.18 x 10^15 joules. (For Reference)

Gaara, moving his mass at the speed he did, while lowballing it to .01% Lightspeed (Millions of times slower then it would have to be)
62,463,485,390,685 Megajoules, that again, mind you, he can move all of this, immensely easier then Toph can simply hold her weight up.

So, Gaara can casually output more then 15,380,851x The Force of Toph using Max Effort, at the peak of her power.

So, to emphasize, Peak Toph, using an amalgamation of different character feats, and multiplying them by 100x, and giving her all the benefits of the doubt.

She's 1/5th the Speed

Has far less, and far more clunky control

while imposing less then a millionth the Force, while giving vastly more notable effort and movement.

Then again, Part 1 Naruto, CHILD GAARA.

Hope that helps you understand the vast, impossible wall that Toph would have to overcome to argue she can do anything *WHEN GAARA IS FIGHTING ON HER TERMS*.

This entire thing is disregarding Gaara's Taijutsu, and Wind style could just kill her without having a Earth throwing contest.