why is my android lagging?

[kassie2015]

my samsung galaxy 5s has been lagging and i've reset it twice and it would be okay for a day and it would keep lagging all the time and i only have a few apps

 

[Black_Dog165]

Do you have an SD card mounted on your phone?

 

[Feldon]

Which version of the Samsung Galaxy S5 is it? What carrier? What country? There are 41 different versions of the phone.

 

[kassie2015]

yes

 

[kassie2015]

t moble, china

 

[Feldon]

Samsung Galaxy S5 is not an international phone. There are 42 different models and each has different 3G and LTE frequency bands which work on some carriers but not others. WillMyPhoneWork.net - Check if your phone works on a network

The Samsung Galaxy S5 T-Mobile variant is SM-G900T. In China, this phone works OK (2G, 3G, one band of LTE) on China Unicom (中国联通). However this phone will have major problems on China Telecom (中国电信集团公司) as there is no 2G or 3G support, and major problems on China Mobile (中国移动通信集团公司) as there is no 3G or LTE support.

Samsung Galaxy S6 improved this situation. Galaxy S7 almost completely solved it (for example AT&T S7 has over 20 LTE frequency bands).