When hovering over items with large amounts of NBT data (with the NBT data display on, of course), It can cause the game to stop responding. This may be due to a performance issue, but it can be annoying to have to turn off if you want to see all of the item's data.

maybe try https://temp.sh/ to upload it to?

Can you please tell me what kind of nbt data you had so I can maybe implement a fix for that. Because, I mean, I could try to optimize my code but I am not sure I that would actually do anything. So can you please tell me something about the item for example?

I can do you one better. If you'd like, I can give you the NBT data of the item(s) (it/them)sel(f/ves). How's that sound?

that would be cool!

Well, crud. Actually, trying to print the NBT data of the item crashed my game! I would give you my hotbar file, but I can't through a comment.