Real peak inside into edublogs performance tricks

So how does edublogs overcome performance issues?

e.g. database timeout issues etc when using the multisite network.

Where do you all host your files. Hostgator?

How do u handling caching AND domain mapping. w3cache seems to be recommended but I can not add CDN support.

I have least that 30 websites on a VPS with hostgator but still experiences database connection issues and other time outs.