Dora Bas Rivka Silver O'H
I'll Huff and I'll Puff and...
We see from Rashi in Talmud Megilla (17b) that this Psalm is a continuation of the previous one.
David wonders aloud why G-d stands apart in times of trouble, rather than taking immediate action. Arrogant, evil people prey upon the innocent. They are so bold as to bless themselves for their blasphemous deeds. (The Talmud in Baba Kama 94a suggests that they say blessings over stolen food, which is blasphemous.) These evil people figure, wrongly, that either there is no G-d or that He will never judge them for their actions. All G-d has to do if blow on them and they will topple over.
These evil people think they are invulnerable and they deceive the innocent with their lies. They lie in wait to ambush their prey, figuring that G-d doesn't care; after all, He's so lofty, we must be beneath His notice. David asks that G-d act quickly on behalf of the victims. He has always looked out for the oppressed, so He will break the hold of these arrogant people. When they stop prospering from their evil, others will stop emulating them.
G-d is King forever. Unlike a mortal king, He doesn't need subjects in order to rule, so He will continue to be King long after man is gone. G-d heeds the cry of the downtrodden and he judges their oppressors so they need be afraid no longer.