I would like to suggest adding API relating to Minecraft's new tick command:
https://minecraft.wiki/w/Commands/tick

Some of the things included:

• Freezing server (stops world/chunk/entity ticking)
• Unfreeze server (resumes ticking)
• Get/Set tick rate (default 20 ticks, can be changed from 1 to 10000)
• Tick stepping (when frozen can slowly progress the ticks along)

Thank you for your consideration