Hmm, lower your FH's video settings a bit. That might help. Also, is the map 513 x 513? Also, if you crash right when you export a map, that might mean the map is to detailed and to strong for your PC. My PC is really strong and relatively new and never really caused any problems (Including no lagging), but maps that are to detailed seem to not be supported.
It's possible your mapped doubled particles in your particles folder in C: >>> Feralheart >> media > particles. Delete any ending in _0, _1, etc. That just means they duplicated.
Gewd luck!
Make sure the "lands" don't touch when blurring or not. (Example: If it is not a heightmap, do not let the lands touch with each other). Usually FH is picky when it comes to this and it will crash at times because of this.