Compile-time memory footprint of std.algorithm

["Nordlöw" via Digitalmars-d]

> tl;dr: allocation is a critical speed issue with dmd. Using the 
> bump-pointer method is very fast, and it matters.

What about packing DMD structure members such as integers and 
enums more efficiently?

We could start with making enums __attribute__((packed)). Is 
there any free static/dynamic tool to check for unexercized bits?

How does Clang do to save so much space compared to GCC? Do they 
pack gentlier or use deallocation?

A much higher-hanging fruit is to switch from using pointers to 
32-bit handles on 64-bit CPUs to reference tokens, 
sub-expressions etc. But I guess that is a big undertaking 
getting type-safe and may give performance hits.