My sony xperia xz is lagging pls help.

hello my name is justin i want to know why my sony xperia xz is lagging from 1% to 5% battery percentage pls help me what can i do in 6% my phone stop lagging when my phone is low battery from 1 to 5 is lagging i check the battery health is okay i dont know why my phone is lagging from 1% to 5% pls help me