I've experienced "brain lag" several times in LDs.

1) standing close facing a wall, running my hands quickly over the surface to feel it, I notice my hands update "at a jerky framerate" like a computer game scene that is too complex to draw smoothly

2) summon a DC who appears directly in front of me as a flat-shaded red person-shaped blob, the "paint" gradually filled in to make it look like a person

3) quickly looking down at my hands in a LD (I wasn't looking down at my hands on purpose, I wanted to summon an object by taking it off of my 'utility belt' and my hands just happened to be there of course so I could "pick up" the object), and I notice my hands are like 3D wireframes in black with white sparkles covering them, then the correct "skin paint" color quickly started covering them.