As you may or may not be aware the item clear also kills guardians and skeletons, as well as dropped items. This also kills all wither skeletons, strays, and elder guardians
Since the elder guardians don't respawn this can be abused to make ocean monuments incredibly easy to raid (with a little knowledge of how the structure generates).

I think I appreciate the reasoning behind killing these two mobs in particular. Skeletons are popular in grinders and can build up to large numbers, and guardians tend to spawn in huge numbers.

Side note: I would suggest adding cave spiders to the mobs killed by item clear. They are also common xp farms and it's likely to find several spawners next to each other. Meaning they can spawn mobs much faster than skeleton grinders.

Anyway back to the guardians. I'm fairly sure that there is no way to kill guardians and not elder guardians. Instead, I suggest not killing guardians at all during item clear. The reason being that the speed with which they spawn makes it pointless anyway.

Here's a few pics to support this:
Item clear just happened:

Less than 3 minutes later we're back to well over 100 entities

Entities then remained somewhere around 150 until the next item clear

Basically, guardians spawn can spawn fast enough, and the item clears are far enough apart that the number of guardians are only reduced for an ineffectively short period of time. With the exception of the elder guardians.

Let me know what you think.
NJB

Caught Gibs

Is this the new Pokemon Go?

I really like the ceiling you've got going on inside. Also want to ask; what are the ladders for in the sugar cane farm?

Avoiding lighting updates might also be a good idea.
For example redstone torches emit light, so contraptions using lots of them can be pretty laggy (e.g. some pumpkin farms use burnout clocks). You can avoid this by lighting the area up so the redstone torches don't affect the light level.

Sadly KatcheD is kind of right, pumpkin farms aren't laggy per se, but your design probably is. Redstone torches are potentially the laggiest redstone component because they cause lighting updates, particularly when you have them in a burnout clock like you do here (I think, difficult to see the redstone)

Check out this video for the evidence: click

@Beedobi What asks but never answers?

A Wol!

It's a known bug that's existed since 1.5. Here's the relevant bug report:

https://bugs.mojang.com/browse/MC-23320

Strange it's happened so much to you though.

Also, I'm sure I saw the ground clear remove hostile mobs. Is this possible or just a despawn coincidence?

@Beedobi A raven is like a writing desk because Poe wrote on both

That's a great answer, and sort of right

@Valgys I vaguely remember reading this in a book back in school. I just remember part of it was academic or something. Ie, it was hard to answer then, probably even harder now given that no one reads old books.

You're right, this is from Alice in Wonderland (which I read last year).

Anyone else have an answer or shall I put you all out of your misery?

@Beedobi can i answer this
even though it might not be the correct or accepted answer

Absolutely, don't leave us hanging.

@TheDunmerRaven Why is a raven like a writing desk?

(can't believe I took this long to think to post this)