When anyone uses a command or chat, they lag. All of these people are on modern, high end devices (including host) but no matter where a command block is, it lags.
Linked issues
Comments 1

When anyone uses a command or chat, they lag. All of these people are on modern, high end devices (including host) but no matter where a command block is, it lags.
migrated
(Unassigned)
Unconfirmed
Windows
Windows 10
1.2.8.0
Retrieved
Thank you for your report!
However, this issue is a duplicate of MCPE-28255. Please add your vote to that issue, and comment there if you have additional information to add.
Also, please remember to search to see if your issue has been reported previously. If you find a similar issue, you can upvote it and/or add a comment with any new information you have. You can also "watch" (subscribe) to it so you get updates by email.