reguitti (12/5/2012)
The thing which is giving me some perplexity is that before the upgrade to a new version of the software which is using this DB...
Not perplexing at all. Someone wrote some code that relies more heavily on statistics or has become more sensitive to a thing known as "Parameter Sniffing". It happens and, if it's 3rd party software, you don't have many choices. Either get them to "fix" it or you need to deal with it, which might require you to rebuild the indexes more often than you have in the past.
--Jeff Moden
Change is inevitable... Change for the better is not.