[Seerah]

My guess on what the OP is asking is this: (Again, just a guess, as the OP wasn't very clear.)

function DoStuff()
     if myTable.var == "something" then
          OtherFunction(myTable.var)
     elseif myTable.var == "somethingelse" then
          NextFunction(myTable.var)
     else
          LastFunction(myTable.var)
     end
end

In the above pseudo-code, you are looking up the value of myTable.var 5 times. In this case, it would be more efficient to assign the value to a local variable and do this instead:

function DoStuff()
     local var = myTable.var
     if var == "something" then
          OtherFunction(var)
     elseif var == "somethingelse" then
          NextFunction(var)
     else
          LastFunction(var)
     end
end

Granted, the gain is minimal unless this code is being executed at a high rate, such as for every OnUpdate or for an event that fires often.