[Grimm665]

Have been running Thunderbird for G-Apps based work email for over a year (Fedora 26,27). Using the Provider for Google Calendar extension works well for integrating calendar into Thunderbird.

Other than fighting with the calendar occasionally (sometimes needing to force a manual sync to see coworkers' events), Gmail in Thunderbird has been pretty smooth. I have not noticed slow search, slow mail receipt, or application crashes. In fact, the search is often too good, in that after running it it matches hundreds of more emails than I usually expect. I usually stick with the quick filter which is a bit less flexible, but generally returns more useful results.

Another advantage, on Linux at least, is that if you copy your ~/.thunderbird folder to another machine, all accounts, GUI layouts, settings, search results, tabs, etc move over flawlessly. I think you just have to re-sign in for Google accounts on the new machine and you are good to go.