Integral Hangs

[parisse]

Unfortunately there is no simplification algorithm, only heuristics.
This integral is solved on the Prime by expanding the exponentials, resulting in a rational fraction of exp(-x), with a denominator of degree 4.
It misses the fact that it can also be expressed as a rational fraction of exp(-2x) with a denominator of degree 2. If you are not satisfied with the CAS answer (whcih is perfectly correct), you can help the CAS
subst('integrate((1-exp(-2*x))/(1+exp(-4*x)),x)',x=t/2) => p; subst(p,t=2*x)
BTW, it's generally a bad idea to try to simplify blindly the result of an integral.
The CAS golden rule for an optimal human/computer cooperation is: the human is the brain and the calc does the heavy computations.