My WordPress Admin panel is too slow.

Hello there,

When i am trying to search plugin am getting this error.

“An unexpected error occurred. Something may be wrong with WordPress.org or this server’s configuration. If you continue to have problems, please try the support forums”

Please see the Screenshot for better understanding.
http://prnt.sc/b6984t

what is the problem ?

and i have an another blog in the same server using WordPress 4.5.2
there is no problem there !!!