Invaders from the Infinite

Possibly the worst science fiction book ever written.
When the good guys are losing a space battle to the aliens, they pop into bubble of spacetime and spend thousands of years developing powerful new weapons, then pop back into the battle a few seconds later with a vast armada to kick butt. I think that's cheating. Like a book on improving your chess suggesting you use a chain saw to dismember your opponent.
I'm sure you can find books you think are worse. Don't tell me. I'm not going to read them to compare. I don't want know. Have it your way.