A lack of self confidence1…
Or What if what I say is stupid and makes me look stupid and …
It could be that the player is feeling that she is lacking in the self confidence to make the "right" choice. Not everyone has the confidence of voicing their opinions, much less making decisions on a fictional character they care about in front of people they respect. It is hard. It is a steep wall to overcome.
What the GM can do
Your under a minute decisions is not helping there, neither is putting pressure on her. This is the worst thing you could possibly do. Instead, try to help her.
First and foremost, impart knowledge to her about what her character can do. Whether it is a system solution (Your skill in X will help!) or telling her that her character clearly would know (That soldier is nothing but a scared bully, you have seen the fear of you in his eyes!).
Second, make sure that she knows what her character can do and when she does support her in that decisions: Show her that any decision she makes is the right one. So, she insults the Underworld Boss. Maybe the boss is wondering what she knows that he does not, so takes it in humour instead of just having her killed.
Lastly but not least, make her understand that even a wrong or bad decision will only make her character's story more interesting, not less. Characters (in any media whatsoever) are interesting when they strive to overcome their weaknesses. It is one of your jobs as GM to make sure this happens and is fun.
Note that actions must have consequences some of which might negatively impact the character. However, a good story does not necessarily mean a good outcome for the protagonists. Look at Heart Of Darkness for a fine example of just that. Or at these frames from Watchmen which spoils the graphic novel's ending if you have not read it:
Rorschach ends up dying because he would not compromise even in the face of Armageddon. This is a superb end to the character's story. Something that stays with everyone who read the graphic novel. Yet, the character dies which is generally seen as a bad thing™. This choice was meaningful, had consequences, and therefore was a good choice.
What the player can do
For the player, I would suggest one thing: Everyone lacks self confidence so we all fake it until we get it. None of your decisions regarding your character are about you. They are about them. You (as the player) can and sometimes should make your character do dumb things. Because it will make the game more interesting, or just because the character lacks the knowledge to make a better choice. Sure, you know Jabba The Hutt is a dangerous crime lord, but your character might just see the fat slug and crack a joke about it.
A related issue is the worry of making a decision that negatively impact the rest of the player characters. If you suspect that your character's action might do that then do talk to the other players. Call for a time out and check that the rest of the players are happy for this action to happen. In turn, when another player does something that negatively affect your character, call a time out and check with them if they have thought of it. The situation might not resolve itself perfectly, but at least you have a dialogue open.
As a player, you are playing a character which could have competences beyond what you have. So, do not be afraid to ask the GM "what someone experienced in X would do?". Get knowledge before making decisions so you can justify your choices, even just to yourself.
Finally, the GM and players (that includes you) are making a story together. You are as much a partner in that as anyone else and are respected by everyone around the table.
1: This answer makes a huge assumption which could be right or not. but none of the other answer really looked at this aspect.