That's already done.
I added an && event.side == Side.SERVER check, which should techically be the same if i'm not mistaken.
I'm a relative Java newb although i have a professioal programming background, but are HashMaps with 6 entries really that bad? (this is not the Forge registry we are talking about, here).
I don't get any damage though, which seems to be contradicting.
Anyhow, still after using either event.SIDE or player.getEntityWorld().isRemote , i still experience the choppieness when double tapping the space bar. I can fly fine after spamming the spacebar enough however that is really an annoying behaviour