There is no universal fix for any kind of performance problem.
What's clear is that you'll need to analyze the problem to understand the cause, and only then you can design a solution of that particular problem.
There may be many different problems, each requiring a different solution. For example, you may have a problem with indexes, with locking, with bugs in code etc. You may want to use computed columns, set-based processing, create a simplified entity for a particular scenario, pre-calculate values before export, import quickly to a another table and run heavy business logic afterwards, and so on and so on.
