My tool kit is heavy, I see now on the web that there are some lightweight multi-tools made from titanium, carbon etc. I carry flip-flops for off-bike walking. Different ways I could cut load weight but most at some cost of money or convenience. I figure that with including my weight & bike weight it would only be about 5% total savings. Every bit helps on the uphills I guess but on flats it's the wind resistance from extra bulk that's the problem.