nasdaq5048,
Take a look at the EL code I wrote at the link below. It should answer your questions.
https://www.tradestation.com/Discuss...Topic_ID=55482
In general, 10-20 charts with an indicator like this applied to it could cause Tradestation to freeze with heavy volume. It depends on how large the array is, how much cycling through the array is required, and how often the code executes (i.e., at the end of each bar or on every tick). Use the Task Manager of your PC to track memory usage and performance while running your indicators during the day with the markets open. For example, I notice that running multiple Time & Sales windows in Tradestation hampers performance especially with heavy volume.
Keep in mind that making this a real-time indicator (updated every tick) will also add considerable complexity to it. Hope this helps.