Seeing a herd of 20+ zebras is cool and all, but not when you can walk 50 blocks and find another large herd!

With that in mind, I'd like to suggest either:

• Reducing the spawn frequency of zebra herds, or
• Making the size of zebra herds more variable (e.g. bound from 1 to 20)

The second option would provide much more variance without taking away the general number of zebras in savannahs, so I'd be in favour of it.
But also reducing the number of herds found in these biomes would make their appearing much more unique, like finding a panda in the bamboo forest.

Entities are one of the laggiest elements in the game, so some default reduction would be appreciated, thanks.

Reduce Deer spawn rate as well
Using Observable

No plans for this internally, we do tweak rates from time to time as we test and they may be tweaked further but sometimes you get lucky and have more Zebra spawn close together

Their rates are configurable via datapack, including Deers

That is unfortunate, a legitimate performance concern was raised so I hope some of the "tweaking from time to time" results in a better gameplay experience eventually now that the team is aware of it.

Making users fix it via datapacks is not a solution to problems.

@bageldotjpg

No plans for this internally, we do tweak rates from time to time as we test and they may be tweaked further but sometimes you get lucky and have more Zebra spawn close together

Their rates are configurable via datapack, including Deers

Excuse me asking this, but where/how is this configurable via datapack?
Looking at the repo the only thing I can find related to the count of zebras spawned is:

int zebraCount = 18 + random.nextInt(3) + random.nextInt(3) + random.nextInt(3);

The rates of the feature itself are configurable via datapack via the zebra_dazzle feature. If you want them to have more traditional spawning you can add a new spawn modifier