An insert or select won't fail because the server's slow. SQL by itself doesn't care how long a query takes. If the procedure is timing out, then it means that the client app has decided that the proc took too long and has told SQL to terminate it.
How you get around that is my optimising your procedure so it doesn't take so long or changing the timeout in the client application.
Gail Shaw
Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability