I train and spar just for fun. But I noticed when I started lifting and started increasing the weights, it affected how I felt when I sparred. My arms feel heavier. It's almost a lethargic feeling as opposed to when I just do roadwork or other training methods. I like the way bench pressing makes my body look but I don't like how it affects me when I punch or move.
Could this be the reason why some of the big weight lifters like Norton, Fruno and some others lacked punching speed? I just don't like the heavy feeling you get from lifting. I think it could affect your ring performance on fight night.