slow rendering with ray mirror glossiness default value

i’m using SVN blender on two linux systems (64 and 32bit), on a simple test scene with ray transp and mirror material, if i set mirror glossiness at 0,999 rendertime is similar to same scene in blender 2.44, while with mirror glossiness set at 1,0 (it deafults to this value), render time is almost double. Is there any particular reason? it seems like setting glossiness to 1,0 forced to a full osa rendering or something like that. is that hardcoded or can be changed? best regards to the whole community