Emacs takes a very, very long time to build (e.g. http://hydra.nixos.org/build/810380). This only happens when chroot builds are enabled. Specifically, compiling elisp code takes very long:

building /tmp/nix-build-1vmkqy0biy0hy3pvh7w4wqmz65aafdkc-emacs-23.2.drv-0/emacs-23.2/lisp/progmodes/flymake.elc
Compiling /tmp/nix-build-1vmkqy0biy0hy3pvh7w4wqmz65aafdkc-emacs-23.2.drv-0/emacs-23.2/lisp/progmodes/flymake.el
Wrote /tmp/nix-build-1vmkqy0biy0hy3pvh7w4wqmz65aafdkc-emacs-23.2.drv-0/emacs-23.2/lisp/progmodes/flymake.elc
[pbuilding /tmp/nix-build-1vmkqy0biy0hy3pvh7w4wqmz65aafdkc-emacs-23.2.drv-0/emacs-23.2/lisp/progmodes/fortran.elc
Compiling /tmp/nix-build-1vmkqy0biy0hy3pvh7w4wqmz65aafdkc-emacs-23.2.drv-0/emacs-23.2/lisp/progmodes/fortran.el
...

Each file takes several seconds. IIRC (from doing an strace once) this is because it tries to do something with the network (maybe a DNS lookup?), which times out after a several seconds. Thus each .elc file incurs a delay of a few seconds.

Submitted by Eelco Dolstra on 17 December 2010 at 11:36