Its unusual to have the TR release take such a long long time ..
When you are releasing the TR , check the below.
a) SM66 for any long running process ..
b) Check in the TP system Log for any messages .
STMS_IMPORT ---> GOTO ----> tp system log..
As mentioned above - is it something abnormal which you are trying to release in this TR .. also is this happening with only this TR or all transports in your system.