I took your script and tested it on my own server. Behavior is what I would expect. So, we...

We're on 2008, so this won't help, however, a possible Hail Mary on this would be to look at columnstore indexes.

Without access to the servers to really drill down on this, it sounds like differences in the optimizer between 2008 and 2012. Every time you upgrade some queries are going...

A query without any kind of filtering such as this is frequently only helped by upgrading hardware. Yes, possibly indexing differently could help... maybe (can't see the execution plan, so...

Back in, I think, 2005, the recompilation behavior changed from procedures to statements. It's a GREAT thing that this happened. Now, instead of any little thing leading to 2, 10,...

Based on the information, nothing but guesses. Differences in parameter values between your test and the actual. Differences in data between your testing and the actual. Differences somewhere are what...

I don't have a clue. Sorry. I'd suggest reporting this to Microsoft as a bug. The main clue that it may be a bug is that a restored database on...

Oh, there's a DBCC command to force simulation. Do an internet search. It's out there.

Without at least the definition of what events you're capturing, filters, actions, it's hard to say. Post the T-SQL.

If you are trying to capture correlated information like this,...

There is an order in which things are executed. It'll help interpret any query you're having problems with.
FROM
WHERE
GROUP BY
HAVING
SELECT
ORDER BY

There's a break...