info:To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
---
# Fast lookup of authorized SSH keys in the database
# Fast lookup of authorized SSH keys in the database **(FREE SELF)**
NOTE:
This document describes a drop-in replacement for the
info:To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
---
# File system Performance Benchmarking
# File system performance benchmarking **(FREE SELF)**
File system performance has a big impact on overall GitLab performance,
especially for actions that read or write to Git repositories. This information
info:To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
---
# Performing Operations in GitLab
# Performing operations in GitLab **(FREE SELF)**
Keep your GitLab instance up and running smoothly.
info:To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
---
# Switching to Puma
# Switching to Puma **(FREE SELF)**
As of GitLab 12.9, [Puma](https://github.com/puma/puma) has replaced [Unicorn](https://yhbt.net/unicorn/)
as the default web server. From GitLab 13.0, the following run Puma instead of Unicorn unless
info:To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
---
# User lookup via OpenSSH's AuthorizedPrincipalsCommand
# User lookup via OpenSSH's AuthorizedPrincipalsCommand **(FREE SELF)**
info:To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
---
# Polling configuration
# Polling configuration **(FREE SELF)**
The GitLab UI polls for updates for different resources (issue notes, issue
titles, pipeline statuses, etc.) on a schedule appropriate to the resource.
info:To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
---
# Set up Postfix for incoming email
# Set up Postfix for incoming email **(FREE SELF)**
This document will take you through the steps of setting up a basic Postfix mail
server with IMAP authentication on Ubuntu, to be used with [incoming email](incoming_email.md).
info:To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
---
# Signing outgoing email with S/MIME
# Signing outgoing email with S/MIME **(FREE SELF)**
Notification emails sent by GitLab can be signed with S/MIME for improved
info:To determine the technical writer assigned to the Stage/Group associated with this page, see https://about.gitlab.com/handbook/engineering/ux/technical-writing/#assignments
---
# Changing your time zone
# Changing your time zone **(FREE SELF)**
The global time zone configuration parameter can be changed in `config/gitlab.yml`: