SQL Server Management Studio 2005 is so slow that I often want to use something command-line just so I can move on with my life and quit waiting for the stupid GUI to load. Have you ever run an update command and have the entire window lock up on you while the query is executing? Those are scary moments right there. How can I speed up the management studio? Is there a "lightweight" alternative?
3 Questions for you:
Is you machine a low end machine? If yes, upgrade. (May or may not be possible. But try to run Management Studio with minimum other apps running). (It works fine on my 2.45 GHz 845 Intel Chipset Motherboard with 1 GB RAM Machine)
Are you connecting to a remote SQL Server? If yes check the network. Make sure that it is not clogged & is fast enough.
Check if TCP/IP is enabled (From SQL Server Configuration Manager). Named Pipes are slow for remote connections (Even for local connections).
You can install SQL Server Management Studio 2008 and still query SQL Server 2005 databases - might be worth a try? I've not had any of the problems you describe with either version though. Are you sure it's not an issue elsewhere?
You could also look at alternativeto.net (but it's currently down).
I had the same issue with SSMS2k5.
I've switched from 'Tabbed documents' to 'MDI environment' in Tools-->Options-->Environment, and it works again well.
You could try TOAD for SQL Server. However, I've only used TOAD for Oracle myself and the past few versions of that have been getting pretty bloated too!