Hello,
There is no way to make NS9750 to run faster if it’s already running at max freqency.
Digi has a wide range of Freescale based modules that RUN Linux from cccwimx28 , ccwmx53, cc6, all of them are much faster but would need a new design.
Latest Linux from Digi for ConnectCore 9750 is LxNETES-3.2 from 2005 with some patches from 2006. It was kernel 2.6.12.5 (different from mentioned 2.6.8 above). LxNETES-3.2 is not supported anymore by Digi.