try use atomic lock in LockedVector. must give some sppedup, but also may have another results :) testing.
Revert "Always cleanup GroupGuid/OriginalGroupGuid while set new group. possible fix bug-using problems, identified after 3023. testing."

This reverts commit 5fa8c94c83209f7288e64948ad7dfddda151ff2f.
Always cleanup GroupGuid/OriginalGroupGuid while set new group or remove from old group. remove static RemoveFromGroup() method - source of problems. possible fix bug-using problems, identified after 3023, also some speedup. testing.