Sorry for the delay in responding. I’ve been doing more tests, mostly with dialogues without any sequences, just text, and in all the tests, it seems that the load is here, but I don't know what the cause is.

Each time the player enters the trigger to call the conversation, there is that micro lag spike, I guess the example I showed on the first post was an extreme one, with the SetActive adding more load, but even without sequences playing, there are lag spikes.
For the game, I'm only using Dialogue System triggers that start the conversation when entering their trigger (also without added sequences), and for the canvas, I’m using the barks that come with the project (with some visual modifications).