Sort of. When I was towing an empty 20+ lb trailer, and the bike +rider was in the 210lb range (so, 10% of the mass) I was about 10% slower than sans-trailer.

Sort of. When I was towing an empty 20+ lb trailer, and the bike +rider was in the 210lb range (so, 10% of the mass) I was about 10% slower than sans-trailer. Towing a trailer + 25lb kid was about another 10%. A lighter bike _may_ feel different, but whether it's weight or something else, or even placebo is up for discussion. It's hard to tell frame weights. 20 years ago, I ran some blind testing where we put weighted waterbottles in a frame, one with lead, one with glass beads, and one empty. 5 trials, A/B, which one was heavier. IIRC, adding 5 lbs of lead was noticable to almost everyone, but the difference between 2.5 and 5 lbs was only noticeable to the frame builder.