A couple of questions come to mind:
First, why did you perform a backup, delete the database, then do a restore? I'm not sure this accomplishes anything, except as a rather drastic way to test whether you have a good backup.
Second, have you looked at disk fragmentation? It may be that your old database was less physically fragmented than your new one. Note I'm not talking about *database* fragmentation, just the physical fragmentation of the database files on your hard drive(s). This could explain why the database is slower than before.
If you really want to do a thorough job, depending on the size of your database, speed of your server, and other factors, you might do a full dump & load, loading the data into a newly-created partition. This ensures that both your physical disk and your database are both defragged.
You also could look at promon, to ascertain what your bottlenecks might be. That's usually a good first step. Depending on your OS, you might also try sar or various NT tools to figure out what the holdup is.
Any questions, just ask. I usually answer email support for free.
Take care,
--Fred Pullen