hmm... or is it that there's a lag dropping into a smaller chainring? That might feel more like a slip. That could be too tight of a cable, a lower limit on the FD that's not set right, or you're shifting from the wrong rear gear (too high on the cassette towards big cogs will mean that there's a huge drop in chain tension such that the shift may not feel smooth or you can drop the chain...too low on the cassette towards the small cogs means that the FD has a hard time pushing the chain to the smaller ring and so the shift is sluggish).