Orochimaru often gets downplayed for having apparently bad reaction feats, but I disagree, so I have pooled together some of his feats and have scaled him off others through direct feats
So let's begin!
Orochimaru stares down kn4 while being completely unaware of whats going on as shown here
Despite having no clue about what's going on, and assuming Naruto paralyzed himself, Orochimaru reacts immediately to a surprise TBB that he didn't know was coming
He also outpaces the travel speed of the TBB and summons the rashomon, Despite all three rashomon summoning after one another, all three raised before TBB could make the halfway mark as shown here. This means Orochimaru reacted to the surprise TBB nearly instantly and summoned just as quickly. The TBB moves quick enough that it's raw speed creates streaks in the air behind it like a literal missile and destroys the ground under it from its sheer speed. It is so fast that it creates an objective mach cone around the blast. A match cone is formed only when a certain speed is met. Neither futon: Rasen shuriken nor a susanoo arrow created a mach cone.
This is also an Orochimaru who is so sick he collapses on the ground after this from his illness
Orochimaru in his lair was completely on his deathbed just after this, his illness rendering his body unable to stand
Despite being in this pitiful state, when Sasuke sneak attacks him, Orochimaru reacts to Chidori eiso despite not even knowing who it was or that he was about to be attacked
What's very important to note is that Sasuke caught Oro off guard and Oro still reacted. This is important because Sasuke did this same thing to someone else and they failed to react to Chidori Eiso despite knowing they were in a fight.
Despite seeing Sasuke jump and also literally staring at the chidori eiso approaching him, Deidara failed to react to the attack and only registered it after it already hit him. He also failed to react to it previously as well, and only surviving because it stopped advancing towards him
If Sasuke's attack had a longer reach, Deidara genuinely would have been hit without a reaction coming from him. That is twice Deidara fails to react in time to chidori eiso, while an Orochimaru on his deathbed reacts to a surprise attack from it.
This is important to note as Deidara can react to Gaara's sand easily
Deidara is able to react to a surprise attack from Gaara, though both times Sasuke uses Chidori eiso he fails to react properly. Meanwhile deathbed stage 4 cancer patient Orochimaru reacts to a surprise attack to chidori eiso.
Gaara's sand is extremely fast as well, being able to block enton and block A4
Deathbed Orochimaru has already shown the ability to react to things Deidara could not, and by extension he should be able to cleanly react to gaara's sand which is already extremely quick. Note A4 needed V2 to dodge enton, whilst Gaara's sand blocked it casually.
Orochimaru also showed good reactions against Hiruzen.
Oro and Hiruzen start from this distance
Hiruzen then charges at him with full speed and throw shuriken that are faster than his own movement speed. Orochimaru runs towards the attack and blocks it with a jutsu, reacting to and outpacing an attack faster then Hiruzen's travel speed.
This is important, as it shows Orochimaur has reactions that far outclass Hiruzen's travel speed easily. Hiruzen With his old man speed managed to arrive on the battlefield at the same time as Tobirama and Hashirama. Only Minato outran them, and they comment and praise Minato for being fast enough to outrun Tobirama. Meanwhile, Hiruzen equals his travel speed
Disregarding this, Orochimaru also saved BM Naruto from the godtree by slicing through all the branches after speeding towards them
This happened after the godtree snared Naruto
These same branches could not protect Naruto from Hiruzen slicing them all up around him and couldn't catch him before he could save Naruto.
Note that Hiruzen is reanimated as an old man, so his speed from his do tensei self is the same speed he had when he fought Orochimaru
Orochimaru while sick can also react to kn4 chakra arms as well, and we know biju chakra is an enormous speed amp
Orochimaru also reacts to CS1 bos Sasuke in cqc distance at a range of less than 2 metres while on his deathbed and pinned to the wall
Had Orochimaru possess killer intent, this would have been kusunagi and this would have killed Sasuke. Deathbed Oro in cqc can easily react to CS1 Sasuke
Given these feats, we can determine Orochimaru has better reactions to Deidara, and therefore can react to attacks with the same speed as or less speed then Gaara's sand. The Hiruzen feats, and the feat of the TBB supplement this as well as the kn4 chakra arms. Orochimaru doesn't have many reaction feats, so I had to fucking search hard To find anything, but this is what I came up with.
Cheers!
So let's begin!
Orochimaru stares down kn4 while being completely unaware of whats going on as shown here
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Despite having no clue about what's going on, and assuming Naruto paralyzed himself, Orochimaru reacts immediately to a surprise TBB that he didn't know was coming
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He also outpaces the travel speed of the TBB and summons the rashomon, Despite all three rashomon summoning after one another, all three raised before TBB could make the halfway mark as shown here. This means Orochimaru reacted to the surprise TBB nearly instantly and summoned just as quickly. The TBB moves quick enough that it's raw speed creates streaks in the air behind it like a literal missile and destroys the ground under it from its sheer speed. It is so fast that it creates an objective mach cone around the blast. A match cone is formed only when a certain speed is met. Neither futon: Rasen shuriken nor a susanoo arrow created a mach cone.
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This is also an Orochimaru who is so sick he collapses on the ground after this from his illness
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Orochimaru in his lair was completely on his deathbed just after this, his illness rendering his body unable to stand
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Despite being in this pitiful state, when Sasuke sneak attacks him, Orochimaru reacts to Chidori eiso despite not even knowing who it was or that he was about to be attacked
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What's very important to note is that Sasuke caught Oro off guard and Oro still reacted. This is important because Sasuke did this same thing to someone else and they failed to react to Chidori Eiso despite knowing they were in a fight.
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Despite seeing Sasuke jump and also literally staring at the chidori eiso approaching him, Deidara failed to react to the attack and only registered it after it already hit him. He also failed to react to it previously as well, and only surviving because it stopped advancing towards him
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If Sasuke's attack had a longer reach, Deidara genuinely would have been hit without a reaction coming from him. That is twice Deidara fails to react in time to chidori eiso, while an Orochimaru on his deathbed reacts to a surprise attack from it.
This is important to note as Deidara can react to Gaara's sand easily
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Deidara is able to react to a surprise attack from Gaara, though both times Sasuke uses Chidori eiso he fails to react properly. Meanwhile deathbed stage 4 cancer patient Orochimaru reacts to a surprise attack to chidori eiso.
Gaara's sand is extremely fast as well, being able to block enton and block A4
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Deathbed Orochimaru has already shown the ability to react to things Deidara could not, and by extension he should be able to cleanly react to gaara's sand which is already extremely quick. Note A4 needed V2 to dodge enton, whilst Gaara's sand blocked it casually.
Orochimaru also showed good reactions against Hiruzen.
Oro and Hiruzen start from this distance
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Hiruzen then charges at him with full speed and throw shuriken that are faster than his own movement speed. Orochimaru runs towards the attack and blocks it with a jutsu, reacting to and outpacing an attack faster then Hiruzen's travel speed.
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This is important, as it shows Orochimaur has reactions that far outclass Hiruzen's travel speed easily. Hiruzen With his old man speed managed to arrive on the battlefield at the same time as Tobirama and Hashirama. Only Minato outran them, and they comment and praise Minato for being fast enough to outrun Tobirama. Meanwhile, Hiruzen equals his travel speed
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Disregarding this, Orochimaru also saved BM Naruto from the godtree by slicing through all the branches after speeding towards them
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This happened after the godtree snared Naruto
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These same branches could not protect Naruto from Hiruzen slicing them all up around him and couldn't catch him before he could save Naruto.
Note that Hiruzen is reanimated as an old man, so his speed from his do tensei self is the same speed he had when he fought Orochimaru
Orochimaru while sick can also react to kn4 chakra arms as well, and we know biju chakra is an enormous speed amp
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Orochimaru also reacts to CS1 bos Sasuke in cqc distance at a range of less than 2 metres while on his deathbed and pinned to the wall
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Had Orochimaru possess killer intent, this would have been kusunagi and this would have killed Sasuke. Deathbed Oro in cqc can easily react to CS1 Sasuke
Given these feats, we can determine Orochimaru has better reactions to Deidara, and therefore can react to attacks with the same speed as or less speed then Gaara's sand. The Hiruzen feats, and the feat of the TBB supplement this as well as the kn4 chakra arms. Orochimaru doesn't have many reaction feats, so I had to fucking search hard To find anything, but this is what I came up with.
Cheers!