If he isn't actually trying in this fight and is still beating Yoda regardless, that means he was toying with him, go learn the definition.
First off, the laughing like a mental patient thing, is George liking the classical evil madman thing. And it's Palpatine happy that he finally gets a chance to fight that little green pest that's annyoed him for the last ten years.
If Palpatine had been able to toy with Yoda, he would kill him instead of toying with him.
Once again again, I'm not saying Palpatine didn't drive Yoda back. I'm saying when some says "Palpatine was toying with Yoda" it is not true.