this random slowness of the phone has happened to others too. me included. i think there was a thread about fixing this.
i up clocked mine to 1GHz and it seems to have solved the problem for me. not saying you should do the same thing but just a tip.

a good clean flash isnt difficult (search wiki for flash guide) and the backup reinstalls (or makes it very easy for you) all the apps. all settings and data is saved - if you leave the emmc alone.
just remember to backup on external storage if possible.