It is common opinion that chapter 2 in BG2 puts CHARNAME into an urgency to save Imoen, because while you are roaming Amn doing quests, she gets mind-raped by Irenicus. Thus, it could be seen as a weak point of the plot because either you go doing all the quests, letting time pass while Imoen suffers and gets her soul stolen, or you hurry for Spellhold, leaving a lot of quests behind.
Actually this in my opinion is not totally true or at least not so much significant.
Cutscenes between chapters show that:
- at the beginning of chapter 2, Imoen and Irenicus are convicted to Spellhold.
- at the beginning of chapter 3, two crowled wizards talk about the possibility of practicing enchantment spells on Imoen. It is not told if this was already done and to what extent. They comment on the cuteness of "the girl they brought in", which means she was just noticed. For what we know, they didn't do anything yet but they would like to do some sexual harassment. Soon after their chat, Irenicus breaks free and goes to a rampage. Then he goes to a still sane Imoen (who replies back), anticipating all the mind-rape that she will from this point suffer.
- at the beginning of chapter 4, we actually see that after Irenicus sized Spellhold, he installed all his machineries and tanks in a large room, filled with captive thieves in order to steal souls with his spells, and then he proceed to steal Imoen's soul (who asks for mercy ---> she had suffered at this point his experiments and torture).
That means that meanwhile, during chapter 2, she is not actually being tortured, but she is simply imprisoned.
CHARNAME doesn't know what's going on, he only knows that he needs 20k gold to seek help. All the major quests could be done, especially because a good character still wants to help people, a neutral character might seek to leave not unbalance behind and an evil character is all for the prize and treasures scattered around. Of course, minor quests like the gong easter egg could be perceived as a waste of time while more important matters are around.
Then consider this thing: how much time is required to transport all the materials and prisoners, build and set up that facility in Spellhold, and then steal Imoen's soul? I think that this takes time, especially because later your travel by sea takes many days. Even if we imagine that Bodhi sent materials during chapter 2 in anticipation of Irenicus' rampage, so that he would find everything he needs in order to start work as soon as possible, hurrying chapter 2 and 3 would mean that Irenicus set up his plan in a snapping of fingers. Thus I think that it is more believable if time is passing while CHARNAME is doing some important quests, rather if quests are left behind and CHARNAME is hurrying to spellhold.
It is chapter 6 that actually puts the player in a hurry because CHARNAME and Imoen both lack a soul and are slowly decaying.