Strange lagg in 1.8 snapshots

I noticed some strange lagg in alot of the 1.8 snapshots.

>> Things that DO lagg:

• Mobs (move laggy)

• The sky (The sky seems to 'visualy go faster' than it actualy does)

• Redstone (Some redstone components, like repeaters have a noticable longer delay)

• Liquids (Liquids spread out far slower than normal)

>> Things that DON'T lagg:

• The chat (Chat works without lagg (Single player & Multi player))

• Commands (Commands don't get effected by lagg)

• Entities (SOME entities do not get affected by lagg like players, Items and Minecarts, but primedTNT does get affected)

I did some more tests with this strange lagg and I found this:

• Nearly always happens in Flatland worlds

• Somtimes go away after some time (~5 minutes)

• Are on SIngleplayer as well as Multiplayer