How to read string slices as integers performantly?

[tim_st]

Assuming I have a string 
    
    
    var x = "aaaabbbbbbbbcccc"
    
    
    Run

of length 16. I want to read the chars "aaaa" as int32, the chars "bbbbbbbb" as 
int64 and the chars "cccc" as int32.

What would be the most performant way to read these 3 slices into the int types 
if I know the start index (here 0)?