The Hair Room hasn't really changed since Poser 5, although they've tweaked how the hair dynamics handle repeatedly, over the years. I believe they switched to handling the hair dynamics with the Bullet physics engine for Poser 10/Pro 2014, but I may be mistaken about that. The Hair Room itself still has the same design tools. You can now grow guide hairs directly on a figure's geometry, however. I guess that's a big change. The old skullcaps are no longer strictly necessary, although they may be useful for something like controlling the hair placement with a modified polygon flow on the cap.

I've been using the same computer since 2011, with Poser Pro 2012, Poser Pro 2014, and Poser 11 Pro. All of these versions have handled decently for me on the same system. Changes to the rendering engine since Pro12 days should give you some rendering speed improvements, whether your device is a powerhouse or not. Firefly got a bit faster with each upgrade, in my experience.

Superfly seems to be the main attraction for most Poser 11 Pro users, but someone else will have to comment on how well it might work with your system. I haven't used it much.

Dunno if it helps, but for reference, here is my system information, according to Speccy:

Operating System: MS Windows 7 Home Premium 64-bit SP1

CPU: Intel Core i5 2400S @ 2.50GHz Sandy Bridge 32nm Technology

RAM: 6.00 GB Dual-Channel DDR3 @ 665MHz (9-9-9-24)

Motherboard: PEGATRON CORPORATION 2AC2 (CPU 1)

Graphics: VA2226w (1680x1050@59Hz) 1023MB GeForce GT 520 (Unknown)

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Cage can be an opinionated jerk who posts without thinking.  He apologizes for this.  He's honestly not trying to be a turkeyhead.

Cage had some freebies, compatible with Poser 11 and below.  His Python scripts were saved at archive.org, along with the rest of the Morphography site, where they were hosted.