Well, the latest 2.3.6 from Aminet (the one with 1.3 MB Bochs executable) works fine here. Can't really say if it's faster or slower than 2.1.1 (seems to be a bit slower, but then, it might just need some tinkering with .bochsrc).

First of all, edit your .bochsrc and make sure the display_library is set to "sdl"! If it's set to "amigaos" the emulator will crash and die!