Thanks. I will try your suggestion. While the speed test servers might see more load in the evenings, I didn't see such erratic and low speeds on optimum with the same tests which I ran just last week. This leads me to believe it's a VZ problem. Perhaps the problem is on a micro level limited to my neighborhood.
A couple of years ago Optimum saw the same slowdowns and they were called out on it. They upgraded their backend equipment soon afterwards which fixed the issue. VZ could be in the same situation.
A couple of years ago Optimum saw the same slowdowns and they were called out on it. They upgraded their backend equipment soon afterwards which fixed the issue. VZ could be in the same situation.