Processing, 78

int x=millis();void draw(){text("Hello world",0,9);if(millis()>x+3000)exit();}

Screenshot:

Y position of the text can be 9 instead of 10, like noted by @ace.

Processing, 77

int x=millis();void draw(){text("Hello world",0,9);if(millis()>x+3e3)exit();}

Screenshot:

Edit 1: Y position of the text can be 9 instead of 10, like noted by @ace.

Edit 2: 3000 can be represented as 3e3 to shave one character off, also noted by @ace

Processing, 79

int x=millis();void draw(){text("Hello world",0,10);if(millis()>x+3000)exit();}

Screenshot:

Y position of the text needs to be set to at least 10 or else the text renders off-screen.

Processing, 78

int x=millis();void draw(){text("Hello world",0,9);if(millis()>x+3000)exit();}

Screenshot:

Y position of the text can be 9 instead of 10, like noted by @ace.