Indeed it is, lipo batteries like to be charged at 1C which is the rate that it would take one hour to charge fully so a 5000mah battery charged at 500ma would take 1 hour. All a fast charge does is charge at a higher C rate which is not good for the batteries lifespan if done repeatedly.

That said the advice I have been given is that if you can do a full discharge and recharge cycle at 1C once or twice a month you should get much better lifespan.