Oh, come on, you don't need a branch to do a conditional subtraction. Reify the condition to 0/1 and use multiplication, or use AND with a two's complement of the condition.
OK, my bit twiddling knowledge is weak, my google skills are weaker still, and now I'm curious: what does "AND with a two's complement of the condition" mean, exactly?
I fully believe that there are plenty of contexts where that's true - particularly in any throughput oriented system where the buffer is large. But if you care, measure.
