Is this because you are using Preview as the texture editor? I use GIMP--maybe this works with Yosemite? Albeit I am not using Yosemite.

You certainly get the benefit of higher binned componnents, but the downside is they tend to be a generation behind. I've seen people try to hack the older gamer hardware with the workstation drivers to get the same results(for less money).

The proven stability of the components combined with drivers geared for the openGL task and better support are what you pay for. Gamers get irritated about these types of cards because they are not gamer freindly, but I don't game so I don't care.

To open your user Plugins folder [i.e. the folder where extensions and plugins get installed by default], you can use this snippet in the SketchUp > Window > Ruby Console:
UI.openURL("file:///#{Sketchup.find_support_file('Plugins')}")
You can of course 'navigate to the equivalent folder - although on a PC it's hidden by default:
C:\Users\YOUR_NAME\AppData\Roaming\SketchUp\SketchUp 2017\SketchUp\Plugins
For other SketchUp versions change the version suffix - e.g. 2016...
Then find the .RB 'loader' file - which creates the extension, and then [re]move it.
Also find the subfolder with the exact matching name, and [re]move that.
Note that some very simple [older] Plugins might not have the matching subfolder...

Alternatively...

The way that the SketchUp ExtensionStore³ 'Uninstaller' works is that it adds an X to the loader .RB file-type - i.e .RBX
This stops it loading, and being listed in the Extensions and Plugins Managers, however, it can be 'Uninstalled' using the toolset - whereby its loader is reverted to .RBB ...

@axton213 said:

decent 3D modelling

That be fightin' talk

In all seriousness though, yeah using sketchup for game-ready modeling is not an efficient use of available tools, to say the least. This thread kinda devolved into what was more fun to use, though, which is ridiculously subjective and not even worth talking about in a forum full of sketchup users.