1. Make sure you have done the default settings image storage, video, audiao recorder, on the memory card instead of internal memory.
2. Menu file manager can be used to remove unnecessary files.
3. If you install applications or games you should select an installation chamber to do to your memory card not to phone memory. Make sure the free 20% of total capacity. If the more full it will slow performance.
4. Optimization of memory with an additional application. For example MemoryUp. How this application works with the set and remove unused files on the memory.
