Verification builds:
1.2.11.4 | All Platforms: Yes

Summary:
It has been reported that there is often significant lag on bedrock Realms. Some of the issues are:

• Quickly breaking blocks causes them to reappear
• Quickly placing blocks causes them to disappear
• When bridging out across lava in the nether, blocks can disappear, pushing the player off into lava.
• Trying to block off flowing lava sometimes doesn't work, and you can take damage from it even though you can't see it visually.
• Rubber-banding type issues with mobs, meaning that mobs can suddenly swarm and kill you, or creepers can suddenly appear and explode before you see them.
• Also when attacking passive mobs, they won't appear to take any damage, and then suddenly die.
• When flying quickly (creative or with elytra) chunks can be very slow to load in.

Many of these were mentioned in a community member's video: https://youtu.be/m1-0V39MvIE

Repro Steps:
(Just a single scenario, any of the above can be reproduced by playing on a realm)

1. Join a Survival realm with other players online
2. Pillar blocks beneath you whilst jumping for some time
3. If you survive that, dig the blocks beneath you quickly

Observed Results:
The block placement lag will often result in you being thrown off the pillar or clipping into the blocks, and if you dig downwards, you may take fall damage.

Expected Results:
There should not be significant block placement/breaking lag

Screenshots/Videos attached: No - but see community member video outlining the issues: https://youtu.be/m1-0V39MvIE

Notes: