Why not just start with the
select queries and see how it performs?
If and when you run into slowness you can always:
- Tweak your queries, use memory tables, get creative with triggers, blackhole tables and whatnot.
- Install a slave server and select from the slave.
- Install a blackhole master and attach multiple slaves to that
I recommend that you read High performance MySQL: http://oreilly.com/catalog/9780596003067