Here are some tips on how to tune Postbox for the fastest performance:
- The initial indexing process is CPU intensive and can consume a lot of RAM. Index your messages overnight by selecting Tools menu > Indexing > Index all Folders. Then restart Postbox to reset your memory.
- You can prevent message bodies from being indexed on an account-by-account basis. Go to Preferences|Options > Accounts > [your account] > Local Storage and deselect indexing for message bodies.
- Set IMAP accounts, set IMAP Limiting to a lower number in Preferences|Options / Accounts / [your account] / Local Storage.
- If you are on IMAP, unsubscribe from folders that are infrequently used by selecting File menu > Subscribe. Unsubscribe from unnecessary folders, then restart Postbox to reset your folder list.
- Delete older messages that are no longer needed.
- Empty your Trash and Junk folders.
- Compact your folders by selecting "Compact Folders" from the File menu, then wait 10 minutes for the process to complete. Additionally, you can set thresholds for when folders should be automatically compressed by going to Preferences|Options / Advanced / Network & Disk Space / and set a lower number for compacting.
- Go to Preferences|Options > Display > Conversations and set "Include messages from" to "the current folder."
- On macOS, remove contacts that are no longer needed from macOS Contacts.app.
- Avatars consume memory, so try turning them off in the following locations:
- Preferences|Options > Advanced > Web Services > turn off "use Gravatar...."
- Display > Conversation > turn off "include contact photos."
Additionally, if you are using Gmail:
- Limit the number of messages that appear in IMAP folders. This can be adjusted at Gmail on the Web > Settings > Forwarding and IMAP tab > Folder Size Limits.
- Consider unsubscribing from the All Mail folder, and use a different folder for Archiving.
- Unsubscribe from the Gmail "Important" folder if you are not actively using that label.
- Use Postbox Topics instead of Postbox Labels, as each time you use a Gmail Label it creates another copy of the message in Postbox.