I hate when I have to take matters into my own hands, but please people, pay attention. (Drivers of very massive vehicles are exempt from this rant--it's a detail of classical physics.)
Freeway on-ramps are constructed for the express purpose of entering freeways. This means you must use the ramp to accelerate until you match the speed of the vehicles already on the freeway.
See, if you decide to travel 40 MPH up a ramp when the traffic on the freeway is traveling 65 MPH, there is a 25 MPH difference. In order to move left onto the freeway, because you are going 40 MPH, you must CUT SOMEBODY OFF, forcing them to slam on the brakes, or force them to move left if they can, or they can simply HIT YOU.
Furthermore, if I am behind you when you decide to travel 40 MPH on the ramp, I will also be forced to go 40 MPH, and must then cut somebody off to get on the freeway because you are preventing me from entering the freeway correctly.
It is easier to get on the freeway if you match speed with the traffic thereon. If you end up with a car next to you, it is simple enough to speed up or slow down to as the situation dictates, in order to move left into an opening. If, however, you are going much slower than the cars on the freeway, you can only hope I'm not killed.