I will try to find one of Jim Muths fractals where he documents the generation time. I will try it under Dosbox then under the Linux version after understanding the local environment. I have some learning to do so this may be a while.
I tried the first fractal on this page... View of a Distant Sea. The time given on this image was 4+ hours although they don't give what environment this is. That kind of time is reliably assumed to be on a Dos system in some way. http://user.xmission.com/~legalize/fractals/fotd/2014/11/index.html I started it in DosBox configuration quite some time ago and it is almost done. Estimated time will be about 3 hours. Meanwhile over in Ubuntu Linux in the Oracle virtual machine (Windows 8 host, Ubuntu 64 guest), it took 2 minutes and 11 seconds. I ran it twice and it was within milliseconds of 2:11 both times. I compiled the latest xfractint and was running it in a local directory. Resolution was 800x600x256 in both tests. Just for the record my relevant hardware. This machine was built about 1 year ago. Asus Z87-A DDR3 1600 LGA 1150 Motherboard Intel Core i7-4770K Quad-Core Desktop Processor Corsair Vengeance Pro 32GB 4 x 8GB DDR3 2400MHz C11 Memory Kit Cooler Master Hyper 212 EVO XFX CORE Edition HD7850 860MHz 2GB DDR5 2x Note that at no time did fans spin up. I did some hunting to try to find other ways to generate the image. I tried ChaosPro which wasn't very compatible. Once I got the par and formula in (I had to edit) I got a blank image. The program hasn't been updated since 2010 so it seems abandoned. Uninstalled. I don't want to buy or try Ultrafractal. It also hasn't been updated in years. That being said, there are no freeware fractint compatible fractal programs. I had said that Fractint was legacy, but now that I see the work having been done on xfractint I take that back. Its the only way to go.