Maybe, maybe not. Depends on the specifics of the queries, among other things. Temp tables aren't a replacement for joins, they're not an automatic performance improvement.
Again, are you sure that the joins are the cause of the performance problems? If so, how did you determine that?
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