I am having a hard time on Cisco's website finding any solid information on subnet sizes. For example, what is the best size for performance and minimizing broadcast storms? What is TOO large? 500? 1000?
No link, but "Top Down Network Design" by priscilla oppenheimer (Cisco Press 1999) notes that pentium class pc's can be measurably affected by 100/second. That may be where I am remembering the number from, but re-reading that section refreshes an important point:
It is the number and frequency of the broadcasts vs the processing power and utilization of that processing power on the attached hosts that makes the final answer. That is probably why answers may vary so greatly. Last thing I found was the SRND for Unified communications recommended VLAN sized at 512 or less, but also states that this is at least in part due to the Call Manager server having an arp cache limitation of 1024 entries.