Here are a few examples of issues raised by software developers related to limitations in the AppVeyor CI service:

https://help.appveyor.com/discussions/questions/41921-appveyor-builds-more-than-twice-as-slow-as-travis
https://github.com/python/mypy/issues/8292
https://github.com/torquem-ch/silkworm/issues/358
https://github.com/quantopian/zipline/issues/2619
https://github.com/henninglive/logitech-lcd/issues/12
https://github.com/wheybags/freeablo/issues/339
https://github.com/Framstag/libosmscout/issues/1034
https://github.com/PlasmaPy/SpectroscoPyx/issues/53
https://github.com/apiaryio/dredd/pull/1804
https://github.com/royaltm/node-murmurhash-native/issues/16
https://githubmemory.com/repo/Framstag/libosmscout/issues/1034