You really need to learn something more about system administration; you clearly don't know what to investigate but this is all fundamental sysadmin knowledge.

First things first - when something is "slow" - what exactly is slow? Is it using excessive CPU time? Is it waiting for disk I/O? Every sysadmin should automatically ask this question first of all, and every sysadmin should know how to tell the difference. If you don't know these things then you are not qualified to be a sysadmin and need to go get training. This is not the forum for teaching you these things.

Copy/pasting someone else's VM tuning settings without understanding what they mean or why they are being set is "cargo cult sysadmin". It is wrong and nobody on this list / in this community should be encouraging it. Quick easy spoonfed answers don't actually help understanding, and understanding is the only real way forward.

In particular, VM tuning settings are highly OS dependent, and probably kernel version dependent too. Good settings depend on exactly what your own system contains; settings that work for someone else may be useless or worse on your own setup.

Simple answers have narrow relevance that gets obsolete quickly. Learning how to think and investigate problems is knowledge that serves you the rest of your life.

As a starting point - what does vmstat tell you? Don't just paste its output here, learn what it means.

--
  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP  http://www.openldap.org/project/