Happy to see you may have pointed the issue.
I'm not surprised about it cause i can remember a mate @ dream match tennis who had the same type of issue using a laptop. The thing was heating and starting to lag, but that was graphic lags, slowdowns. In dmt it didn't translated in slow/floaty play but simple slowdowns/sluttering from his side, and from the opponent side, one could see him warping (cause in DMT online play, both players are not "synced" to a fixed delay like in TE).
Dektop PC and ethernet ftw
As Uchiha said, be sure your laptop can "breath" enough from the back, not laying on a cloth or so, there always need to be some space between the laptop back and the surface where it's installed. If it's not enough, well.. then you'll probably face a problem ... heating is often an issue with laptops unfortunately. I guess there is laptops dedicated to gaming wich are better cooled, but costs an arm and barely come close to a desktop in the cooling area.