Variable add / delete takes too long.

Every added / deleted variable causes a 30 sec delay while large number of blocks get synched.
Other changes like editing blocks are immediate.

It actually depends on the variable name. If the variable name sorts to the end of the list (e.g. it starts with lowercase "z") then fewer scripts will need to be recompiled. If the variable starts with "AAA", it will probably force recompilation of all scripts.