id	summary	reporter	owner	description	type	status	priority	milestone	version	resolution	keywords	cc
17	folds for unboxed vectors are slow.	Khudyakov		"I found that fold based functions which operate on unboxed vectors are much slower (~7-50 times) than functions which operate on generic vectors. Benchmark is in attachment.

{{{
-- Slow function
mean :: U.Vector Double -> Double
mean = ...
-- Fast function
mean' :: (G.Vector v Double) => v Double -> Double
mean' = ...
}}}

Here is profiling results. '''U''' column is for mean, '''G''' is for mean'.
{{{
       | U(ms) | G(ms) |
foldl  | 47.3  |  1.08 |
foldl' |  6.54 |  1.09 |
foldr  | 44.3  |  1.99 |
fodlr' |  7.44 |  1.02 |
}}}
It looks like that monomorphic variant isn't properly optimized. Results are consistent between GHC6.10.4 and GHC6.12.1.
"	defect	closed	major		0.6	invalid