After the 1.10 update my realm's players and I started experiencing severe lag when opening our inventory or a crafting table when we have skulker boxes in our inventory. This delay can be as long as 5 seconds which in a dangerous situation (pvp or when mobs are around) is not an acceptable delay.
This was fine in 1.09 and I think was corrected in an early 1.11 beta, so please fix this in the released version ASAP.
Additionally and possibly related, there are lengthy delays in bringing up the UIs for anvils, crafting tables, looms, brewing stands, etc. when used for the first time. This has been an ongoing issue for some time, but throughout various betas I saw the delays increase/decrease depending on the release. In the 1.10 non-beta release they are significantly delayed.
We have this same problem. Shulker boxes cause very bad lag in inventory and any window that opens like horse inventory or chests or craft tables. I agree it can be very bad, as i found out, especially around creepers.