Why send_sms method runs slow?

I have configured and generated some OTP’s for an hour. But now the send_sms method is working very slow.

Its the Issue with background jobs. I am seeing dozens of this line on console

5:40:31 worker_short.1   | 15:40:31 short: frappe.utils.background_jobs.execute_job(async=True, event=u'all', job_name=u'frappe.email.doctype.email_account.email_account.notify_unreplied', kwargs={}, method=u'frappe.email.doctype.email_account.email_account.notify_unreplied', site=u'rati', user=u'Administrator') (e69fb499-77ed-4a25-9622-b0bd3e76c4cf)
15:40:31 worker_short.1   | 15:40:31 short: Job OK (e69fb499-77ed-4a25-9622-b0bd3e76c4cf)
15:40:31 worker_short.1   | 15:40:31 Result is kept for 500 seconds
15:40:31 worker_short.1   | 15:40:31 
15:40:31 worker_short.1   | 15:40:31 *** Listening on short...

I am using sms service but in the background jobs its showing some issue in email service.Why so?
and How to run send_sms method fastly?

Thanks in Advance