How to find out why finder hangs when "as List" / "as Columns" / "as Cover Flow" on Yosemite
The problem is/was Google Drive. As of early October they silently released a new version 1.32 that might have solved the problem but since that one hasn't reached my system yet I will get back to it later has solved the problem. All the versions since then work fine, including the new "Backup and Sync".

Version 1.31 intermittently fails only on Mac OS X Mavericks (10.9.5) but disabling the visual notifications solves it; upgrading to a newer version also solves the problem.

Some references:


others having the same issue: https://productforums.google.com/forum/#!topic/drive/TeXBYS4qH0g and https://productforums.google.com/forum/#!topic/drive/rzdrkYWlgGc
solving on Mavericks: https://www.maketecheasier.com/fix-google-drive-crashing-finder-in-mavericks/
version 1.32: http://www.macworld.co.uk/download/internet-tools/google-drive-13233635836-3328202/