The few times I rode over 100mph years ago, what amazed me was the wind and vibration trying to pull my hands off the grips- I have a small National Cycle brand windshield added that helps a lot for a bike with no fairings over 50 mph, with tall handlebars. The quality of the clear or tinted plastic is better from this company, for a reasonable price.
Also, the speed that telephone poles go by on the edge of road compared to a normal speed seems a lot different. I only did this a few times on long straight roads that I knew well in rural areas, with no driveways and no police around and no other traffic.
I was foolish enough to take some smooth corners on my 1978 650 Yamaha until the frame or exhaust pipe scraped the ground, in posted 35 mph corners at 60 mph, and one time in the early 1980s in my 1972 Plymouth Barracuda I slowly built up over several tries to 85 mph in a 35 mph corner so that all 4 wider than stock tires were sliding but I stayed on the road barely, then gave up going this fast. Now, I never go over 85 mph, and only to pass sooner on 4 lane highways when the car in front of me is going 65-70 in a 70 mph zone.