Okay.. so I do not know what has happened to the enchant 'obliterate' recently, but there has being some odd things going on lately. Players with the obliterate enchant + drill seem to lag the server immensely. The excavation enchant + obliterate does lag the server but in terms of comparison to drill barely.
I have provided both a video of a comparison of drill and excavation with the enchant obliterate. In the video with drill you can see that when I start to mine the server lags immensely, and I look into that by breaking blocks one by one to see if anything odd happens... and it turns out that when a drill went down it triggered obliterate and any of the blocks the obliterate enchant broke triggers drill to go straight down also. I am not sure if this could be considered infinite and that it could trigger it a 2nd time, as this would be quite hard to get to happen with Obliterate III.
The reason why I believe drill is wayyy more laggy then excavation is that you can use drill infinitely, where as with excavation the animation needs to end before it can start another excavation, unlike drill where it does not.