Look up the one click lag fix in the market. It will root your phone and apply the lag fix for you, mine is really fast now.
Also did my friends with no issue.
Once you open the app it will say root, click root, then you have to shut down the phone, then hold volume up and down, home and power, then once it says galaxy s i9000m let go, it will go into recovery mode, use volume down to go to apply sdcard.zip, click home, it will do that then reboot.
Now go to the one click lag fix again, then you will have to choose "check free space" or something like that.
Then click install lag fix, I did about 1000mb.
After you do the lag fix, it reboots the phone for you (a second time), the screen will go black with the buttons on the bottom lit up, take out the battery, then reboot. It will take a little while to reboot this time but it will work. Boot up doesnt take long after that one time.
Download quadrant from the marketplace and your quadrant score should of went from about 800 to over 2000.
Heres my phone with beautiful widgets, launcher pro, and switchpro... Launcher pro with the lag fix is really speedy and I have no lag. Before I did it with my friends phone I couldnt believe how laggy it was.
3d app drawer