pc lag

[aman]

depends on a number of factors !

are you asking about regular usage or internet browsing & downloading ?
-- allround
which laptop, how old it is ?
-- 6th year  :D
which processor, how much RAM ?
--i3 2gb ram
harddisk capacity & its free space
--500gb and more then half free

how is booting speed ?
--normal mostly, maybe around 30-50 sec
does it have many application  programs ?
-- basic but few extras, antivirus, firefox, chrome, editors
does it have antivirus with up-to-date definitions ?
--- latest avg
have you tried ccleaner like utilities ?
-- did tried bleachbit
have you tried reconditioning [cleaning inside ..]
-- that about not sure but not long ago, when given to reinstall windows, shopkeeper opened it and maybe cleaned