Thought I might share a little guide I’ve compiled. Enjoy. =)
Restore + Jailbreak Steps
- Perform full restore from iTunes with stock 3.1.2 firmware
- When prompted to “Restore From Backup,” decline and choose Setup New iPhone…
- Download blackra1n, and run it to jailbreak the iPhone: http://blackra1n.com/
- Once Jailbroken, install Rock, Cydia, and Sn0w.
- Run Rock to update, and exit. Then run Cydia to update, and exit.
- Open Rock or Cydia and install MobileTerminal, Aptitude, and APT.
- Change your passwords for “mobile” and “root” users!
- Install OpenSSH and respring/reboot.
- Optional: Run the following commands to install the most used software through an SSH session:
- apt-get install bigbosshackertools com.ericasadun.utilities
- apt-get install rotationinhibitor sbsettingsinsomnia notifier irealquicksms
- apt-get install jp.ashikase.kirikae backgrounder us.scw.afctwoadd
- apt-get install com.weiphone.setwallpaper3 com.saurik.iphone.fid
- Performance Improvements: Remove unnecessary LaunchDaemons
- cd /System/Library/LaunchDaemons
- rm com.apple.DumpPanic.plist
- rm com.apple.ReportCrash.*.plist
- rm com.apple.CrashHouseKeeping.plist
- rm com.apple.aslmanager.plist
- rm com.apple.syslogd.plist
- rm com.apple.powerlog.plist
- rm com.apple.stackshot.server.plist
- rm com.apple.tcpdump.server.plist
- rm com.apple.iqagent.plist
- rm com.apple.mobile.profile_janitor.plist
- rm com.apple.chud.chum.plist
- rm com.apple.chud.pilotfish.plist
- rm com.apple.AddressBook.plist
- rm com.apple.datamigrator.plist
- rm com.apple.AOSNotification.plist
- rm com.apple.AdminLite.plist
- Performance Improvements: Remove unnecessary Language Packs
- apt-get install find
- updatedb; locate lproj | grep -E proj$ | grep -E -v -i ‘(en.l|English)’ > langpacks.txt
- while read file; do rm -rf “$file”; done < langpacks.txt
Williamo's Blog 
I like the guide, never tried any of those performance tweaks though. Are they really that noticeable? Currently I have large amount of mobile substrate processes running and no tweaks with no signs of slow performance on my 3GS.
Why Jailbreak
I can definitely notice the difference after the tweaks, though I have a 3G, not a 3GS – your phone definitely has enough horsepower to handle all the mobile substrate processes and has quite a bit more RAM as well. =)
While the direct performance improvements might be slight after removing the extra language packs and launch daemons, the difference in free RAM is pretty significant (approx. 20MB extra free RAM after the tweaks).
BTW, which mobile substrate processes/plugins do you have running?
i have a different problem –
jail-brake etc and everything was fine – one day the little icons for text messages stopped showing and i only had a box – then cydia started crashing – i deleted because i still had installous as well as rock – the phone eventually just crashed and i had the apple logo in and out on the screen..
Tried to black rain it again and only to the same – tried to restore to 3Gs 3.1.2 which was what i was running and apple is saying that my phone is not eligible for restore..
Tried this fix:
http://modmyi.com/guides/restore-iphone-3gs-3-1-2-using-shshs-file-cydia-windows/
I get:
cannot create c:\windows\system32\drivers\host
can anybody assist?
Comment on the last Post – the official message is:
the iphone isnt eligible for requested build