Same problem here. The mouse speed is just fine, until I start the media station. After that it just gets too slow. This must be the right speed for low resolution screens. Should be configurable, I guess.
It seems that lmce must run a script when you start the media station that resets these setting to some defaults. I guess this is a hangover from the Pluto releases where there was know kde desktop giving easy access to these settings.
Cleary now they should either be left alone by lmce and then the user can set them easily using the standard kde desktop features or some ability to set these defaults needs to be provided in the lmce manager app.