breastfeeding: how long does it take your 4.5 month old?

My LO seems to take a LONG time to breastfeed.  Often 25-30 minutes, 6 times/day. clearly sucking and swallowing the entire time.  I know my supply is good since I get a good amount when I pump (and my boobs are engorged).  Any advice as to how to make her a more efficient eater?  Her latch is great too .... I went to a lactation consultant early on.  Hoping introducing solids will help but I'd like to hold off until 6 months.