Turbo Boost Switcher

Turbo Boost Switcher sits in the menu bar and lets you disable or re-enable the Turbo Boost feature of Intel processors, which can keep a laptop cooler and quieter and extend battery life at the cost of peak speed. It does this by loading a small kernel extension, so it asks for an administrator password and, on recent macOS versions, a one-time approval in System Settings.

It only applies to Intel Macs with Turbo Boost. The free, open-source version is downloadable from the project website and Homebrew; a paid Pro edition with automatic modes is sold separately and is not covered by this listing.