I recommend using Easy Engine for Multisite and all other kinds of WordPress setups.
Information below is probably outdated as this post of from 2011 but I’ll leave it here, there might still be some good info.
Links to the best caching and tuning options and methods for WordPress Multisite on VPS or dedicated servers.
- Great thread on Stackexchange about caching options for Multisite on non-shared hosting
- Support topic on wordpress.org about Multisite on high performance nginx
- WordPress Optimization Bible by Vladimir Prelovac
- MySQLTuner is a script written in Perl that will assist you with your MySQL configuration and make recommendations for increased performance and stability.
The quick fix
Looking for a simple WordPress caching solution that just works? Get Quick Cache. Hardly any settings and a huge performance gain. I highly recommend it. This website uses it, judge for yourself.
Links to new resources are highly appreciated, please leave them in the comments and I’ll add them here.