[rohansahai]

Been on RDS for awhile now but have recently had some issues that are pushing us to heavily consider EC2 - especially since we've heard about considerable performance gains running on some of the bare metal EC2 options out there vs RDS.

[mijoharas]

We had equivalent performance (and we'd benchmarked both) for equivalent RDS and EC2 instances. (EDIT: to note, we didn't dig in heavily, just looked and saw it seemed the same, maybe there's something smart you can do to make EC2 a lot faster)

First thing to think about for RDS (or any postgres instance really) is to figure out what the bottlenecks are, if your cache hit ratio is slightly low, or queries are generally feeling a little sluggish but cpu and ram aren't too high, I'd recommend looking into increasing the provisioned IOPS of the machine (requires no downtime, basically you can just make the storage faster).

If your issues are ram/cpu being high you might want to consider moving to a larger instance.

It can also be worth looking into the number of temp files being created by your queries and tweak your work_mem setting (you can use log_temp_files to see if this is likely to help a bit).

Other than that, remember that every connection to the db is a separate process, so you don't want too many. It could be worth looking at RDS proxy or pg_bouncer if you think you have a lot of connections to your db.