Yes, after a restore Froyo re-downloads all of the apps you had before. So actually, if you have any apps that are causing problems right now it will just re-download it, which may defeat the purpose of this whole thing. Have you gone into Applications -> Running Services to see what's eating up resources? It could be that just a couple are using up way too much memory and deleting them alone will solve much of your lag.
In my experience so far, the only services that seem to be necessary are:
- Contacts / Cache Service
- Backup Assistant
- Google Services Framework
- Data Manager Service
- Sync Service
- Usb
- Global Unplug
- com.motorola.android.syncml.service
Although I bet one or more of those could be removed too, I just haven't bothered to investigate. So in short, anything other than those services can be removed. Some like Skype, NewsWidget, and WeatherWidget can only be removed through root. Others like WidgetLocker and Swype obviously only run because you use them, which is fine. If there are any apps that you've downloaded that are running services and you rarely or never use those apps, get rid of them!
Other tips for reducing lag:
- Don't use taskkillers
- Try ADW or Launcher Pro
- Only use widgets that you actually use
- Remove Skype and other bloat (root)