It's compatible. The JAR version of the launcher runs just fine, no need for complex workarounds with the EXE.
As for the 1 fps, make sure you have proprietary graphics drivers installed (or any at all), maybe running straight from the jar will fix some problems too.
Also note that ubuntu ships as 32bit standard which is complete bollocks, I tried running FTB under 32bit java once and it was almost unplayable; this may well be your problem.
Just run java --jar FTB_Launcher.jar (or make a launcher out of that command if you're lazy)
Right now there is a linux-specific bug in the modpacks (they will launch without mods), the workaround being to rename /instMods/minecraftforge.zip to /instMods/MinecraftForge.zip