Edited: I bought D'or Vitesse/2 [Se]. I freaked out thinking it wasn't in my inventory, but apparently the consumable was automatically used or something? I sure as hell didn't do it, so that's probably another bug. Anyway, the main problem here is that this somehow made my computer start running like absolute garbage afterward. The game and everything else on my computer plummetted to feeling like molasses and even restarting my computer didn't fix anything. Nothing I tried to do to fix it worked until I deleted the SEGA folder in my documents, which has since made everything work normally again, but it shouldn't have happened in the first place...

Additional edit: The moment I restored the SEGA folder, my computer started lagging to death again. I deleted both my action log and activity log from the day of the occurance and the day prior (yesterday and the day before, I did this yesterday) and it started working again. Did something go horribly wrong in the action log related to how I did not use that consumable, but was counted as having immediately done so?