The BEST way to speed it up is to just disable EVERYTHING at Settings>Today>Items. No Sense, no windows default, no date or time, no not nothin.
Reset the device, and you'll find that everything is snappy and instant and the phone is 100% usable. Memory consumption will run 30-55%. Life is good. Figure out what buttons/info you need, then install lightweight plugins and cabs to customize the home screen.
I go for these:
Pocket Digital Clock: Has SECONDS!!! hold to set alarms.
Keyswop-Assign the softkeys to what ever functions you wish.
jd TaskManager-Enables the super useful task manager button, Top/right corner.