I assume you are currently on the Pro plan?

Yes

It is still too slow

We're dealing with ~500 active users

And you are aware of the $1000/m minimum of the Enterprise plan?

And can you confirm that the reason your application is limited is due to hardware constraints?

is there a way to increase memory and connection limit on pro?

per usage?

There is no connection limit, and the maximum memory per service is 32GB with a maximum 32vCPU

I’d suggest looking into replicas