Server crashes(cause of plugin)

First of all Hello,
I am new in this forum and actually do not now if I'm right in this section. Excuse me for my bad englisch but I'm from germany.
I wrote a few plugins with skript and everything works fine but in one specific plugin(1v1.sk) when I challenge a player(several ways: damage with diamond sword; /challenge; /accept) the server crashes.
Now I don't know if my servers(used different ones) are just too slow or if there is an fault in my skript.
Thanks a lot for help.
Here are the two links:
Skript:
https://pastebin.com/CigZyeTA
Server log:
https://pastebin.com/tJATRBVh

 

Please help me:
Server console says:
Cannot write variables to the database 'default' at sufficient speed; server performance may suffer and many variables will be lost if the server crashes.
Then the sever crashes.
Whats wrong?

 

only worldedit and skript-plugins.
I am shure that my skripts are making(sorry for that englisch) those errors, but what exactly does this error say?

 

How do I do this[Also if anyone speaks german, that whould be awesome]?