Chrome 57 has been released recently. This version introduces background tab throttling to help improve performance. This is important to know about for workers because many important scripts you use can be affected by this. Throttling of background tabs already existed, slowing them down to only be able to run once every second, but now they are going to be limited to an average of 1% CPU usage. Affected scripts HIT Finder HIT Catcher Panda Crazy Overwatch HIT Scraper Turkmaster HIT Monitor Affected browsers Chrome Chrome Canary Chromium Opera (?) Vivaldi (?) (?) denotes unconfirmed, but they are based off of chromium so they should be when their bases get updated to Chromium 57+ How to opt-out Windows: Right click the shortcut you use to launch chrome and select properties. Add --disable-background-timer-throttling to the end of the target line, there needs to be a space separating it as pictured below. You will have to exit out of Chrome completely for this to take affect and always use the edited shortcut to launch chrome or the flag will not run. Mac: Enter this into the terminal Code: /Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome --disable-background-timer-throttling You will have to do this everytime you launch Chrome or you can follow these instructions: https://turkerhub.com/posts/106128/ Both: You can verify that the flag is enabled by going to chrome://version and seeing --disable-background-timer-throttling under "Command Line". How to know if a tab can to be throttled Any background tab that is not playing audio or does not have a WebSocket/WebRTC will be throttled unless you opt-out. HIT Finder would not be throttled since it is in the foreground HIT Finder would be throttled since it is in the background. Having the scripts in their own window will prevent them from being throttled as long as they aren't minimized. You can have other windows covering them, just do not minimize them to the system tray.