The Problem

i am unable to place a structure that is VERY LARGE without the server or game frezeing and crashing

A Solution

make worldedit not place or edit all of the blocks at the same exact time so it reduces the load on the game

Alternatives

No response

Anything Else?

i am on forge and can not use plug-ins and the structure is millions of blocks in size (this should help people who are designing large maps too)

Async (or rather, parallel) placing cannot be done safely with Minecraft's model. Spreading it out over ticks could maybe be done, but is not something we are likely to implement soon.

Yes spreading it over ticks seems to be the safest way because placing in too many blocks at once just crashes the game or server