The SQL Server process will gradually
(running a week or so) take up about
80-90% of the memory so there must be
something hogging the server.
If I would get a cent every time someone did not read the documentation and asks this question, I would be a billionaire.
SQL Server, bya stanmdard configuration, uses ALL AVAILABLE MEMORY AS CACHE. To speed thigns up.
If you are not OK with that, go to the server properties and tell SQL Server how much memory it can use. It will gladly adhere to this.
Otherwise, again, every data read is cached. Point. Old pages are released as new ones read in.
Because readingfomr discs is SLOW.
Most "real" sql server installs run on dedicated machines. Which makes teh default behavior HIGHLY desirable.
Nothing wrong here except the Admin did not care to configure SQL server properly ;)