id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	os	architecture	failure	difficulty	testcase	blockedby	blocking	related
2438	memory performance problem when compiling lots of derived instances in a single file	claus		"I'm playing with deriving `Data/Typeable` for the GHC AST types (you'll need a recent HEAD for the standalone deriving fixes #2378, and I've got to use the generics-internal CPP tricks to work around #2433).

After getting the first compiler-complaint-free version of the instances source, self-same compiler went away and tried to get all the memory it could find (I had to kill the process). After splitting the source into two, one importing the other, there is no problem loading them anymore. 

- `Instances.hs` imports `Instances0.hs`: loading `Instances` into `GHCi, version 6.9.20080709` works fine.

- `All.hs` merges the source of `Instances` and `Instances0` into a single module: trying to load `All` into `GHCi, version 6.9.20080709` consumes memory like crazy.

Compiling `All.hs` shouldn't behave like this in the first place, but if just splitting the file into two helps, the compiler should be able to do the split implicitly (sparing me the manual dependency analysis)."	bug	closed	normal	6.10.1	Compiler	6.9	fixed			Unknown/Multiple	Unknown/Multiple	Compile-time performance bug	Unknown