I don't like threaded email views as much as the inline "conversation view" of gmail, however gmail is not as fast as I'd like it to be. Are there any desktop clients which provide a "conversation view"?
You can get something along these lines via the Thunderbird Conversations addon. I haven't used it recently but when I did (a year or two ago) it was usable, though not quite as smooth as gmail itself. It is being actively developed, so it has likely improved since then. Reviews seem to be mostly positive, though it may not work with all versions of TBird.
You might want to take a look at sup. It is curses-based, so text mode only.