I am first going to address, as I understand it, your two points. The first, unless I am mistaken, is comprised of two (admittedly, overlapping and thus logically inconsistent) claims concerning the Senate and what it was designed to do. In order of appearance: (a) The Senate was designed by the Founding Fathers to act quickly and (b) this is reflected in the Constitution. The second is more straightforward, and is composed of three parts (a) an indictment that filibustering isn't a "time-honored tradition," (b) it wasn't used "at all" before the civil rights era and finally (c) it wasn't used widely until the 1990s.
I am going to address the second one first, because it is much easier to demonstratively disprove.
Filibustering is a "time-honored" tradition stretching all the way back to the Roman Republic; more specifically, Cato the Younger
[Link]. This tradition has extended through France and Britain (most spectacularly over the Irish Question), until arriving in American in 1841 in the famous debate between Henry Clay and Calhoun following the removal of the "Previous Question Motion" in the Upper House. I believe this, along with the following examples, unequivocally disproves (a) of your second claim.
Moving onto (b) of claim (2), where you state it wasn't used until the civil rights era. On April 24, 1953, Senator Morse began to filibuster against Tidelands Oil legislation. He kept the floor for 22 hours and 26 minutes, breaking the filibuster record of 18 hours held by his mentor, Wisconsin Senator Robert La Follette. Neither of which are part of the civil rights movement or of the era. There is also the example of the famous Senator Huey Long who filibustered for a then-record 15 hours on On June 12, 1935.
Finally, the idea that the filibuster was not widely used before the 1990s is absurd; as you well know. I believe this
[Link] is evidence enough.
At this point, any fair-minded person can conclude that filibustering in America does have a long "time-honored tradition," that it existed well before the civil-rights era was well used extensively before 1990.