Well, lag is because a bunch of older and new players all started playing now that the game is free. Or so I assume.
And as for performance, I had to adjust my video settings as they got reset the the latest patch. Before I did, my fps was really low from the new settings.
As a casual player I was satisfied that at one point I had a char max level and near max crafting with almost all motifs and I pretty much lost interest. Then ESO discovered DLC's and now my main is just a wanabe and I am happily pulled back into the game.