Try freeing up memory space by closing programs that are not in use. To close them follow:
1. Tap Start > Settings> System tab > Memory > Main tab to check the current available phone memory.
2. Tap touch Running Programs this checks which programs are currently running on your phone.
2. Select the programs that you want to stop running, (so they get exit from Memory) and then tap Stop. To end all running programs, tap Stop All.
Now your phone will be alot more faster and smoother in working.
