Thunderbird
MZLA Technologies·Open source·thunderbird.net
Definition maintained by @wes. clients/thunderbird.json
Coordinates checked by snapshot with version 144 on macOS 15.4 (October 2026).
Reading its numbers
- Thunderbird keeps no offline copy of Junk and Trash by default; the other 95% of the mailbox it holds in full.
Results
Each column is one run. The place is among the clients in that run, lowest first; within one display frame of the fastest counts as a tie. Runs are not comparable with each other.
| Test | 250,000 messages◐Mac Studio, October 15, 2026version 158 | 50,000 messages◐Mac Studio, October 14, 2026version 144 |
|---|---|---|
| Open a message | 74 ms2 of 6 | 56 mstied for best |
| Next message | 339 ms4 of 6 | 305 ms5 of 6 |
| Search | 433 ms3 of 6 | 372 ms4 of 6 |
| Launch | 3,603 ms6 of 6 | 2,171 ms6 of 6 |
| Quit | 128 ms5 of 6 | 97 ms4 of 6 |
| Scroll | 580 ms6 of 6 | 571 ms6 of 6 |
| Memory | 1,040 MB6 of 6 | 1,148 MB6 of 6 |
| Idle CPU | 2.5%4 of 6 | 4.1%6 of 6 |
- Search. The Quick Filter, Thunderbird's search-as-you-type, looks at sender, recipients and subject by default but not the message body, which is less work than full-text search.
Setting it up
Install
brew install --cask thunderbird.
Add the benchmark account
Server 127.0.0.1, port 10143 (10144 for the 250k mailbox), no encryption, user bench@example.com, password bench.
- Account Settings ▸ Add Mail Account ▸ Configure manually. Connection security None, Authentication Normal password.
So it holds the whole mailbox
- Under Synchronisation & Storage, turn on "Keep messages in all folders for this account on this computer". Without it Thunderbird syncs headers only and wins by not doing the work.
- Set mail.server.default.max_cached_connections to match the other clients (5).
For a first-sync measurement
- Remove the Bench account in Account Settings and quit Thunderbird.
- Press Enter here, then add the account again, with the setting above.
Its window
Default "cards" layout with the Quick Filter bar left open; it stays open across launches, and the list sits below it. 66pt cards, reader to the right. The search field is cleared with its own × and never with select-all and Backspace, and never closed with Escape: Backspace in Thunderbird's message list deletes.