Is there a practical limit to the number of hosts that should be allowed on a subnet on a single VLAN in a switched environment? In the past I've typically subnetted to a maximum of say a /23 with 510 hosts. But I was thinking I don't have a logical reason for that. The one issue I can think of is more hosts on a subnet on a VLAN means a broadcast gets forwarded to more ports. Are there other conserations in choosing number of hosts per subnet? Thanks.
you have already listed the most important reason to limit size of subnets: broadcasts.
Vlans are broadcast domains they confine broadcast traffic and routers are broadcast firewalls (unless converting with helper-address in something else).
With 65000 hosts in the same network the probability that some host is doing ARP or something else that involves broadcast will make the network resources and host CPU resources (because broadcasts must be processed) are wasted.
Reducing broadcast impact is one of the key elements in network performance increase and also helps stability.
On the other hand, in a switched network creation of a new Vlan has no cost because it is a built-in capability (there are some limits on STP scalability on smaller platforms).
Routers allow for creation of Vlan subifs and routing protocols are now classless.
So /23 is a reasonable max size.
Hope to help