effective epsilon-constraint:

G. Mavrotas introduced an improvement of epsilon-constraint method using lexicographic optimization for the payoff table. The new method is called AUGMECON and is included in gams libray.

see other improvement

2 manners to get "The time of execution" in gams.

1. Using function:  timeExec

see Manual 

2. Using function: jnow

startTime = jnow;
...
elapsedTime = (jnow - startTime)*24*3600;

see wiki