I just tried it out, but it doesn't work the way I hoped it would.
I was hoping for some kind of SIGSTOP equivalent on any JavaScript when the tab doesn't have focus (without unloading anything). Instead, it basically closes the tab but leaves it on the tab bar, and when you return to it the tab gets reloaded.
I know what you mean, and yeah unfortunately it doesn't work that way. I have js disabled on almost everything anyway, but having a way to pause js would indeed be delicious.
Total suspender is great not just for memory but for CPU. I reduced a lot of unnecessary CPU consumption by having the tabs not in focus frozen after a few minutes.