There is a thread Event Frame Attributes Not PI Tags which should answer my question, but it doesn't...
My event frames have many (100+) attributes configured as table lookups, with time consuming SQL queries behind them. The attributes seem to be calculated correctly. But when I open Event Frame search results, it takes very long time to update the displayed list. Why? It should be displayed instantly - everything should be known and nothing calculated. As I understand the concept of Event Frame attributes, they should be calculated once, when EndTime of Event Frame is written and remain as static values forever (or until changed programmatically). But it seems that something is retrieved from the SQL-table later, when client application asks for a attribute.
I also noticed that when I change the template - add some new attributes as table lookups - for EF already generated, the new attributes are calculated (correctly) when I try to display them. I expected rather static "No Data", "Null" or similar, but not a series of queries regarding historical event frames.
Could anybody explain, what exactly happens with EF attributes that are table references?