While you're at it... long ago, I measured the if against assignment, and the assignment won... But that was back in VFP 5 or 6, so... can you compare this to your other measurements?
kcString = REPLICATE("a",100)
a=SECONDS()
FOR y = 1TO 100000
lcstring = ""
lcComma=""
for x = 1to 10
lcString = m.lcString + lcComma+kcString
lcComma=", "endforENDFOR y
?"create comma each time",SECONDS()-m.a