Firmware updates take care of lags, bugs, and other issues that you may not be aware of. Such issues crop up with reasonable frequency, so updating regularly will ensure the best performance for your phone.Memory issues
Low internal memory might be the reason behind any severe lag that your phone is experiencing. Move your media (pictures, MP3 files, videos, and so forth) to the external memory, usually an SD card. Some low-end and mid-range smartphones might already have low internal memories, in which case, moving your files to the SD card won’t help that much.
The application store of your phone, regardless of which OS it uses, will have plenty of apps that can help boost your phone’s performance. Task managers help you monitor and close unnecessary processes. This frees up some RAM memory, and so, the phone will run faster. A good antivirus application will scan your phone for any possible viruses and malwares, which can also slow down your phone.