> and packages it works just fine at the default of 10M (for my 36M), and
> there is, indeed, a noticable speed-up. 

That's good news. I'll have to try that next time I compile a kernel!

> distributed binaries. They tend to dump core, and give seg faults. X does
> screen scrolls faster than dt, but it didn't compile with any
> optimizations!  X's generated makefiles don't seem to respect CFLAGS. 
> I'm not sure if there is a simple way to govern the entire build.

To make global changes I think you can change the .cf file for netbsd. The
.cf files are used by imake when generating makefiles (I *hate* imake!).
I think it's somewhere in the X source tree under something along the lines
of lib/config.