Yesterday I got really tired of how slow my rooted Samsung Galaxy Spica I5700 was. Up until then it was so slow that I had to wait like 10 seconds before the SMS window would show up. It was rooted with LK2.08 and I had also installed SamdroidMod Kitchen. But yesterday I downloaded the latest “normal” firmware to Galaxy Spica and installed it with Odin. The installation went fine, without bricking my phone. 
And it is sooo fast now compared to LK2.08! It feels so fun to use it now. I can’t understand why the phone became so slow with my previous configuration. However, if you want to unroot your phone and/or update the firmware of your Galaxy Spica, here are some useful links: