It can depend on the device and where the variables end up, but here's a contrast of the two methods (post #2, post #6)
Code:
invar    #2    #6
$00      64    34
$01      64    36
$55      64    42
$FF      64    50
That's for an 18F26K22. Results are in instruction cycles.
Post #2 has the "advantage" of always taking 64 cycles, but #6 is always faster.