SCCM OSD run very slow

hi,

I am using sccm 2007 R3 and i have a primary site and secondary site.

i have 2 task sequences, for windows xp(sp3 x86) and windows 7 (enterprise x64). in both of them, after the OS part i am installing some programs (7zip, Office, etc).

for very long time i used BITS and the osd was fine (it took a hour to deploy a machine xp/7).

i edit the configuration file of the iis and add "requestFiltering allowDoubleEscaping="True"" and suddenly the task sequence of windows 7 takes above 10 hours, and the xpremains the same.

the OS parts (when the WinPE download the .wim and the drivers) work good only the programs download takes forever and only in windows 7.

i try to delete the "requestFiltering allowDoubleEscaping="True"" but it didnt help.

now i disabled the BITS and the osd work fine again.

what could be the problem that its work very slow with bits?