First, I don't recognize the workspace, and from the time I've spent with the EGP, that's not a layout that seems efficient to me. The EGP is where you control things like text and spacing of items in the screen, the ECP is where you animate things, which is why the 'standard' Graphics/EGP layout has the EGP down the right side, program monitor above the right side of the timeline, and the ECP above the left side of the timeline. I'd recommend staying with that layout while you're building experience with this graphics process.
Second ... they dumped folders for the mogrts in the 12.x builds (2018 series) ... as it is designed internally around the Libraries, which can be either/both local or in your CC Cloud space. As you can have multiple libraries, you can use that feature to group mogrts. A lot of use are arguing from returning full local folder options to the users, and you are most welcome to post a request for that on the UserVoice system or jump onto any other request for such that you find via a search on that system. That way it gets to the development team, the only staffers regularly on 'here' are the product support people.
Adobe UserVoice Bug /Feature form: https://adobe-video.uservoice.com/forums/911233-premiere-pro
There's no way I know of to install full folders of mogrts at this time, you need to install them one at a time via the little rectangle with a plus-sign icon in the lower right corner of the EGP. Not the slickest thing, mind you. But ... again, ask for change.
Third ... that is just bizarre how other things work normal speed and only graphics things works slower. Using a slightly modified version of the standard Graphics workspace, it works the same speed as anything else.
I've been editing on Premiere for over a decade and am pretty obsessive with optimizing my layouts (and shortcuts, etc) so a lot of thought has gone into the workspace layout (I customize the presets to fit how I work)
Hopefully we'll discover why (only) my EGP is so sluggish for me.
Its not just you, I just posted similar problem. Even working in a 1080p nested sequence, using the eseential graphics workspace I only need to have a text layer and a rectangle before it slows to a crawl.