Char vs. String for Dict key

New to Julia
6

And symbols are as fast as chars:

julia> @btime isequal(:a,:a);                                                                                                                         
  1.689 ns (0 allocations: 0 bytes)                                                                                                                   
                                                                                                                                                      
julia> @btime isequal('k', 'c');                                                                                                                      
  1.688 ns (0 allocations: 0 bytes)                                                                                                                   
                                                                                                                                                      
julia> @btime isequal("k", "v");                                                                                                                      
  5.033 ns (0 allocations: 0 bytes)