Experience build up in furnace when using a hopper which can cause severe lag

This is probably caused by the fix for MC-126150.

FYI I hope the furnaces storing xp feature can be kept.  In survival mode, it will encourage autosmelting without wasting XP, much better than manual smelting and collecting all the time.   Also it allows creations like these:

Further to the video linked above, Xisumavoid has tested and made some inventions:

Minecraft 1.13 Furnace XP Farm - https://www.youtube.com/watch?v=UgRUYmaYDlE Sep 9, 2018
(demonstrating it is possible to connect a furnace array to automated farms making a slow AFK XP farm, also demonstrating duration of smelting of different items required to reach 30 levels.

Minecraft 1.13 Instant Item Repair System - https://www.youtube.com/watch?v=uskkb72uIkk Sep 16, 2018
Contraption limiting amounts that get smelted so XP amount matches XP required to repair different items using a redstone counting system.

Minecraft 1.13 XP Storage Silo Tutorial - https://www.youtube.com/watch?v=8bdj_Uk3L_0&feature=youtu.be  Sep 22, 2018
Simplification of above item repair system using an autosmelter array.  Player can manually place filler items to set and limit the number of items smelted and the XP produced.

Yes, but it can also cause huge amounts of lag, hence it's tracked here.

Yes, violine, I understand as it is, a large amount of experience released at once could crash the game.  Perhaps, like Xisuma said (in the top video linked there), they could limit the XP a furnace can store so it wouldn't crash a server or lag out.  It'd be good if that experience limit amount would equal. at least. 30 levels, if possible. It'd be great to keep this feature in the game. 
(Another use is, Xisuma has cleverly made a community furnace in Hermitcraft Season 6, charging hermits to smelt there while storing the experience for his use. lol)

If not a limit on the XP storage, perhaps there are other another ways to reduce the experience_orb entities released from a furnace to prevent crashes?

SKOOT4life added the below suggestion to a suggestion on r/minecraftsuggestions "Make brewing give XP like smelting"

"XP orbs can be an object of their own. These cant be used at all, and are just objects limited to inventories and storage. However when combining a set amount of them with a glass bottle a bottle'o'enchanting can be made. The reasoning for this is that when things are smelted and then extracted with a hopper, you dont get the xp from them. So the furnaces can release xp orb items into the hoppers allowing you to collect the xp later on and use it."

I know violine and have contributed to bug reports on here before!  I put that here for two reasons:
1) to show the community has embraced storing xp in furnaces as an feature and improvement to the game that came with 1.13.
2) If XP could be stored in containers in stacks as an item that would solve unlimited xp being released at once from a furnace.  It would add a new dimension to many xp farms.  It probably requires a lot of coding but the technical players would embrace that.

I will delete the above and this comment if you think it's not relevant at all to this bug report and clouds the issue.

It could be considered a bug that the XP orbs just store xp up to 2477 points (spawning without commands) (from the wiki).

If the maximum capacity for the orbs get increased, it would reduce the number of orbs/entities needed, and thus reduce the lag. And it would be super simple to code it (devs you can do it pls :d)

Should be categorized to performance

It can be possible, but it's just "can be possible". Smelting 1M cactus with 1 furnace takes about 4 months and only produces ~400 xp orb entities, which is not a problem for the server. And no one will try to lag a server using this

This might need to be reopened, it looks like the same thing happens if the hopper is locked, not removed.