Lisp Questions - reading a file and processes stalling

[Jeff Clough <jeff@chaosphere.com>]

I've got a few questions I'm hoping someone here can answer.

First, what is the lightest weight way of getting the contents of a file
into a buffer?  Stepping through insert-file-contents and
format-insert-file (with the requisite nil) seems to involve huge
numbers of calls and a lot of winding/unwinding the stack.  I have a
function that wants to open thousands of files, examine them then put
them away.  This is obviously slow and I'm wondering if I made some
boneheaded error in using these functions in the first place.  To be
fair, my code is slow for reasons other than this, but I'm taking one
lump of molasses at a time.

Second, I have Emacs running an external program as a process.  When
some other lengthy operation is happening elsewhere in Emacs (like Gnus
is trying to display the headers for a group*), that process stalls,
then picks up where it left off once the operation is done.  Is there
any way to make Emacs not steal the resources from this process, or am I
doing something hopelessly wrong?

* - Yes, I'm running Gnus now.  Those who remember my earlier rantings
    can feel free to slap me around.  I still hate it, but it's proven
    to be better than Mew.

Jeff