MacOS – Why do two Chrome windows launch when I click an external link

Enabling "Warn Before Quitting" should prevent that from happening. You can find that option in the Chrome menu in the menubar.

When enabled, you need to hold down ⌘+Q for a bit before it actually quits.

This is the common problem which can be related to anything, like:

• Chrome bugs,
• network issues (check logs at chrome://net-internals/),
• active extensions are slowing down web browser in general,
• performance issues (either your machine is slow or you've too many tabs opened),

• slow disk access, especially when your cache folder is huge with too many files.

  E.g. you may consider moving your profile folder into quick access drive.

Here are few suggestions:

• restart web browser (also kill all chrome processes),
• run in Incognito mode, to see if this could be related to some slow extensions,
• create a new profile with no extensions and see if that helps,
• install addons which aims limit the page processing (e.g. OneTab, ad blockers),
• run Chrome in different user data dir (--user-data-dir="<some_path>"),

• run with --disable-hang-monitor to suppress hang monitor dialog,

  Suppresses hang monitor dialogs in renderer processes. This may allow slow unload handlers on a page to prevent the tab from closing, but the Task Manager can be used to terminate the offending process in this case.^peter.sh

• make sure Chrome uses GPU process to enhance performance (see: chrome://gpu/),
• generate network log file at chrome://net-internals/ and report the issue at bugs.chromium.org.

Debug suggestions:

• check: chrome://flags/
• check debug network log file generated by chrome://net-internals/
• run chrome://tracing/
• see other internal Chrome pages at chrome://chrome-urls/.