Unfortunately lots of FAWE and some AWE versions have problems in their APIs, which means our maps won't save or load properly.

Example:
#405

We recommend contacting their support team. You can review our code, I am not sure what I can do because we're simply using WorldEdit functions and FAWE changes them...unfortunately.

But, we do have anti-lag feature for vanilla WorldEdit so you can just use that and you maps will load in chunks to avoid freezes.