I wanted to contribute a small piece of code (#1071, a low hanging fruit, not ready yet).
After every change I do recompile idris using make, which seems to rebuild the whole project, even if only one or two source files changed.
This takes quite an huge amount of time (~5 minutes) on my machine:
$ uname -s -r -v -m -p -i -o
Linux 3.13.0-43-generic #72-Ubuntu SMP Mon Dec 8 19:35:06 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
$ ghc --version
The Glorious Glasgow Haskell Compilation System, version 7.8.3
CPU: Intel® Core™ i5-4210M CPU @ 2.60GHz × 4
RAM: 8 GiB