i m using 9780 Bold with carrier Etisalat-UAE
my device was working well in UAE ,

as soon as i reached at Pakistan airport (on vacations )
I changed sim and switched on my BB , it was very slow

next day I activated BIS from Mobilink and I rebooted (pull out battery) but it was still very slow

I uninstalled almost all other applications ,videos , photos but same result
whenever i m typing a sms or bbm text , the device is hanged for few seconds

plz help| guide me to fix this issue

are you in an area with a good signal? Do you have GSM, GPRS, EDGE. or 3G displayed?

This is probably due to a combination of only having EDGE service at the most (there is no 3G at all in Pakistan), and also because mobile traffic must go through Pakistani government servers.