Estimated Time vs. Actual Time - Pronterface

I’m using Slic3r and Pronterface.

The “estimated duration” time Pronterface computes is typically pretty far off from the actual time it takes to print.
I usually double what I see in the estimate.

Today was the worst I’ve seen yet though.

Pronterface estimated about 2.25 hours - print took 7 hours.

Is anybody else seeing something like this? Am I missing something in the software that grossly changes the estimate from the actual?

Is there a way to narrow the gap between the two numbers?

The estimate’s really general- I’ve seen prints with accurate estimates, and prints with wildly off estimations. Cura seems to be a bit more on point in the past few prints I’ve ran.