looking for a particular spell

[Titania, the Summer Queen]

I want a spell that would advance time on a person so that effects from a poison or curse so that it all of the effects take place in one round.

[Kayerloth]

What's your goal here? A cinematic effect, to make a bad thing far worse for a foe or to somehow benefit the target by 'getting over' the effect sooner? I don't know of any such spell written specifically for any of the above.
But having said that maybe a Create Greater Demiplane and manipulating the Time trait would do the trick for you.

[DM_Blake]

What are "all the effects"?

Poisons, for example, usually have a fairly small effect that can happen over and over for a length of time that cannot be predicted because it depends on the victim's Saving Throws. If the victim makes one (or more as necessary) good Saves right at the start, the poison may wear off very quickly, as fast as 1 round, with no effect. But if the victim makes a dozen bad Saves in a row, the same poison could last for a dozen rounds and do it's small effect a dozen times.

So, based on that, what you really want is some way to force the victim to make a number of Saves in a single round and suffer the effects according to the normal poison rules but accelerated, so he might still make good Saves and resit the poison entirely or bad Saves and take lots of harm.

I don't know of anything even remotely like that, but it might exist in a supplement somewhere. Maybe someone else knows of it if it does. Otherwise, you'll have to make it yourself. The real problem is that the power of the spell is entirely based on the power of the poison - suffering a few extra effects from a weak poison may be irritating, but suffering a few extra effects from a very strong poison could be deadly.

This is compounded by the fact that, normally, a poison victim can do something every round to save himself. Take an Antitoxin, ask his cleric friend to remove the poison, receive necessary healing, etc. But if multiple harmful effects are all accelerated into one round, the victim has no time to get help. Which is probably at least part of your intent here - I'm just saying it can turn fairly weak poisons into killers.

[Tarantula]

Are you looking for accelerate poison?
You hasten the onset of poison in the target. If the poison normally has an onset time, its effects begin immediately. If the poison has no onset time, its frequency is doubled, requiring two saving throws and inflicting damage twice per round or minute, though its duration is halved. Accelerate poison does not change the cure condition for the poison. If the target is affected by more than one poison, you may choose which is affected if you administered the poison; otherwise, randomly determine which poison is affected.

[Pizza Lord]

Maybe a custom spell like:
Compress Poison
Target: One poisoned creature

If the targets fails a save against this spell, all poisons affecting it are treated as though additional time has immediately passed. The accelerated time is equal to 1 rd./3 caster levels for poisons with frequencies timed in rounds or 1 min./3 caster levels for poisons with frequencies timed in minute or longer intervals. This acceleration will shorten the onset time if the poison has not yet begun to affect the target.

Due to the effects of this spell, affected poisons are easier to resist. Each additional save beyond the first caused by this spell gives the target a cumulative +1 bonus to resist.

Example: A 9th-level caster using this upon a target just poisoned with Bloodroot (1 rd. onset; Freq 1/rd. for 4 rds.) The spell causes 3 apparent rounds to pass with regards to the poison (1 rd./3 caster levels), 1 round uses up the onset time and the target must save twice immediately (with a +1 to the second save) or suffer the normal penalties for each failure. The Bloodroot still has 2 rds. of potency remaining. Similarly, the same caster targeting a creature just poisoned by Black Lotus Extract (1 min. onset; Freq 1/rd. for 6 rds.) would cause 3 apparent rounds to pass for the poison, but this would only shorten the onset time without requiring the target to save against the poison.

I don't really know Pathfinder mechanics that well and I'm leaving spell levels and such out of it. I put the +1 cumulative save there to account for preventing targets from being able to drink anti-toxin or restoratives that would otherwise mitigate overpowering poisons. I didn't see any typical poisons with frequencies other than rounds or minutes, but I added that it was the same for those with longer frequencies just to cover the bases.You can tweak it as suits, it's just a suggestion for a potential solution, I make no claims that it's perfect.