Encoding in pentium PC havin windows OS

[irfan]

Hello every one.....
i am working on a telephony application and i am taking data from mic
as input at a rate of 8KHz 16 vit mono (128 killo bits per second) . I
am trying to encode this much rate of data using MELP encoder... which
encodes 360 bytes of data means 180 samples of data in about 47 milli
seconds during normal execution where as i want it to be accomplished
in about 22.5 ms...
Now i try to use multiple threads to bring this processing time down
to some extent but as i increase number of threads the time creaps
up..... I am certain that its just bcz of the scheduling that takes
place between the threads that takes time higher..... All the threads
have the same priority .... now i am confused that what to do .... is
there any other possible solution ...
can i accomplish this CPU intensive work using multiple threads in
windows operating system on a pentium processor with 1.60 GHZ
processing speed.............
i shall be thankful for ur kind help
thanks
irfan