hi sir,
as per your issues I suggest you to try to change your laptop battery for the charging issue. in 98% cases with same issue it is in need to Change battery.
and the other thing is related to slow processing it is depend your configuration and installed application. if you think the configuration is lower and you are using high performance applications then it will always slower. you can try with make free space in your c drive, clean temp files, create Virtual space machenism, and replace HDD with SSD.