im confused about the setting of the interruprt flag i.e,bit 1 of intcon register for using xternal interrupts......i wanna know where it should b cleared...shud i clear it inside the isr itself? i,e. before retfie?....or else where and how should i clear it...

i tried clearing it just before retfie in isr....the program worked when simulated but found that it is hanging on to the last instruction for a long time.....that is it is taking much time to return to main code......
sme one give an explanation..........