The airlock on the carboy with the currants was much, much faster than the quart sample. I imagine it might be possibly due to the smaller container, but I don't think that is the case.
Absolutely the size of the carboy matters when it comes to how fast the bubbling is. Imagine two containers, one of which has 100 L, the other has one L. The must in them is identical otherwise, and the airlock is the same on the two of them. The 100 L volume will produce 100 times more gas per second than the 1 L jug,, but this gas has to go out through the same-size hole! It will take more bubbles per second for that to happen.