Redmine

Environment:
  Redmine version                3.3.2.stable.16427
  Ruby version                   2.0.0-p648 (2015-12-16) [x86_64-linux-gnu]
  Rails version                  4.2.7.1
  Environment                    production
  Database adapter               Mysql2
SCM:
  Subversion                     1.8.8
  Git                            1.9.1
  Filesystem                     
Redmine plugins:
  no plugin installed
OS: 
  Ubuntu 14.04 Server

When I go to update an issue, it takes anywhere from 5 to 20 seconds to update (show the next view of "success"). This happens for every user, and it happened while I was on version 3.2 as well. When googling this, the first thing I came across was SMTP settings, and I thought for sure that would be it because it was close to the same time that we moved to office365 email settings that the problem appeared. I'm not 100% sure that the issue happened at the same time as the change, but it could have. But, after changing to async_smtp, there was no speed change.

I believe the SMTP settings are correct for async, since emails are being sent successfully. I'll post them here anyway, just in case it's still not actually sending using the async method.

default:
  email_delivery:
    delivery_method: :async_smtp
    async_smtp_settings:
      address: "smtp.office365.com" 
      port: '587'
      domain: "mydomain.com" 
      authentication: :login
      user_name: "user@geeksandnerds.com" 
      password: "MyPassword" 
      enable_starttls_auto: true

I haven't seen anything odd in /var/log/apache2/redmine.access.log, or redmine.error.log. Is there anywhere else that I can look to see what's causing this delay? Any help is appreciated.