Slow . . . or swift?

I've been enjoying my "through-the-Bible-in-a-year" reading program.

Early on, I got four days ahead of the pace. Sometime, recently, after a missed a few days and almost fell behind, I actually sped up and, as of this morning, finished the reading scheduled for May 27th. --I say all that in case you happen to be following a similar program and wonder why I would be reading in Psalms already. . . .

I titled this post as I did not to reference how slowly or swiftly I've been reading, but, rather, to notice Psalm 2:12:

Kiss the Son, lest he be angry . . . for his wrath is quickly kindled.

????!!!!????

I thought:

Now, wait a second! Aren't we supposed to be "slow to speak, slow to anger" (James 1:19)? . . . And, actually [once I looked up the phrase slow to anger on BlueLetterBible, I was reminded . . . ], "slow to anger" is one of God's fundamental characteristics according to Exodus 34:6-7 where God proclaims His Name to Moses:

[YHWH--Jehovah] passed before him and proclaimed, "[YHWH], [YHWH], a God merciful and gracious, slow to anger, and abounding in steadfast love and faithfulness, keeping steadfast love for thousands, forgiving iniquity and transgression and sin, but who will by no means clear the guilty, visiting the iniquity of the fathers on the children and the children's children, to the third and the fourth generation."

--ESV

So which is it? And/or, how are we supposed to understand these passages? Is David (or whoever the psalmist is) saying something by which we are supposed to understand we should be taught, or is he "merely" expressing a personal opinion? (I assume, when we have Moses actually quoting God, we ought to consider that portion of Scripture definitive.)

In sum, then: How should we interpret these passages when they at least appear to be in conflict one with the other?