old Iphone 3GS play music all the time memory full?

Hi guys, I used my old Iphone 3GS to play music at our spa.
I control it with Veency from my CPU (it is jailbroken)
its running on iOS 4.3.3.
Downside is, I leave the screen always on so I can always control it via veency (it cuts the Wifi =T, anyone got a solution for that?)
and thus, my touchscreen has became unresponsive, but after a while, it came back.
But the problem is, if I dont reboot it once in a while, it becomes really slow, such as cant start my music. Even tho when I double click, I only see 1 app running (Music).
So does anyone know any tricks to make it run smoothly? thanks guys =)