Does SQL profiler affect server performance?
SQL Server Profiler is a GUI that utilizes SQL Server Trace through the client-side.  Due to this nature, yes you can potentially see a mild to severe performance impact depending on the environment.

SQL Server Profiler is suited mainly for a quick glimpse at what is happening on the server (provided the database server can handle the extra latency).  It is not intended to be run for long periods of time.  For longer traces, use a server-side trace or Extended Events.