Not just RSI... ALL Custom Columns... To explain it better, TOS sends near real-time data for any and all symbols you are monitoring, whether in Watchlists, on Charts, in Active Trader, etc as they are part of the standard data stream... It doesn't parse the database on the server continuously to make sure your Custom Columns are calculated but it does try to get to them at least once every 3 - 5 minutes... Custom Columns are considered lower priority as every one of them in the database for ALL users requires server resources to calculate and deliver and it is for this very reason that they have a lower priority... I hope this adequately clarifies the differences in priority...