Well, I'm no expert and no pro for sure. But my bike logs show me slower when I've tried the 32mm and such on the few bikes they fit. Could be nothing more than the bike feels slower and hence I am slower. IDK nor really care. I truly like how my bikes feel under me with my 25mm tires and just don't see a reason to change. And of course I doubt even 5 or 6 of my 30 bikes would even fit something bigger than 28mm. I do run some fatter tires on some of the bikes because they suit the purpose of those bikes. Off the top of my head of my head both the Poprad and the PT-3500 are running either 35 or 38 GK slicks.

My Avalon is a lot more comfortable than my Miata on the road and is certainly faster in most situations. But if I want fun, I'm taking the Miata. My bikes are no different.