Of course the CPU will be at 100% when you're compiling a program.
A common myth, while this is the case for 16-bit DOS programs, most newer and resource demanding programs like games use a DOS extender wich means they can address up to 4GB of memory as one linear flat segment some even support virtual memory. DR-DOS is very good in this respect, it includes a multi-tasker which can perform mult-threading and a built-in DOS extenter.
Yes, and DR-DOS has DPMI built in, so you don't have to downlaod CWSDPMI or run Windows 3.1 to use 32 bit DPMI programs. DR-DOS is really a very advanced, feature-rich DOS, but most of the DOS programs I ran were 16 bit, except for games.
Anyhoo... I found a page you might like
http://www.drdos.net/faq/Has some nice DR-DOS system tweaks.
