Hi alpduhuez, keep in mind: when the dll is deployed in the .xap file, it is compressed to ~160K.
If you really needed to squeeze out more bytes here are a couple additional tips:
Since the source code is available you could look for classs & xaml not essential to your specific app and remove them. I understand this creates a potential maintenance burden going forward for you but it might help.
You could create an application library cache file for SMF so it wouldn't have to get updated when you updated and redeployed your xap file. This won't help with 'first launch' time but will make updates smaller going forward.
If you don't need SMF right away in your app you could dynamically download it at runtime in the background. You should be able to find tips on the internet for do this.
Hope that helps, Tim Greenfield