How to reduce file size of assemblies

Hi Guys,

I do have an assembly (20,445 KB) which was given by the client and, it has a lot of component inside. Were when I open it in Solidworks prompts a warning saying that, due to so many components in the assembly It may affect the performance.

How do I reduce the file size without affecting the scale of the components inside.

SolidworksAssemblies