[Phanx]

Originally Posted by Clamsoda Edit: In response to Torhal's suggestion of not using select(), should I just upsource the select() function, or use something similar to: <code>

If those are the only options, then you'd use the code you posted. Calling functions is sloooooow, even if they're upvalued.

However, since your code is only handling one event, you can just name the arguments as they're passed to your handler:

frame:SetScript("OnEvent", function(self, event, timestamp, combatEvent, _, sourceGUID, _, _, _, destGUID, _, _, _, amount)
     if combatEvent == "SWING_DAMAGE" and destGUID == PLAYER_GUID and knownTypes[tonumber(strsub(sourceGUID, 5, 5), 16) % 8] == "NPC" then
          damageTable[time()] = amount
     end
end)

On a side note, strsub(<string>, 5, 5) is faster than <string>:sub(5, 5) even if you don't upvalue strsub, and way faster if you do.