High-performance compilers conventionally sort the field of objects
by alignment restriction so that space isn't wasted between fields.
In the present system short, char, byte and bool fields all use a
full word. This simplifies interpretation but wastes space and impacts
cache efficiency. The problem is worse when words are 64 bits.

It would be better to compute an optimal packing at class load time;
the speed of compiled code would be unaffected.