We have the same problem with the new MBPs, Glyphs and LG 5K monitor – Glyphs app is lacking in the overall workflow down to resizing windows. And we are not using Wacom. We do though experience this in the Adobe CC 2017 as well, but not on a general Mac OS level…
I do not notice much difference with or without the LG5k connected to the MBP, I just wonder how do I get some tabs on one and some tabs on the other screen to fully use the massive screen real estate? Did you install the LG screen manager software?
Glyphs is still mainly a single window app. There are some options to use the second screen: the preview panel, the TextPreview app, Indesign or a web browser.
a web browser over LAN? 
How to?
You can build a HTML file that uses the local font with @font-face and reloads itself every second. Then you overwrite the font by exporting from Glyphs and you see the updated page.
OK I though there is a secret ip number allowing to preview a font inside a browser window
Here is a LINK to a short screen capture showing the interface lacking when dragging a shape around… 15" 2017 mbp with LG5K…
Can you disable all plugins and try again?
So, now I have systematicly gone through my plugins and removing RMX makes a huge difference! There is still a tiny bit of lack, but when removing RMX there was a noticeable difference…
Are you sure it was RMX? It is not doing anything when not called by the UI. Can you do a spindump(*) of dragging stuff around with RMX installed?
*) In Activity Monitor ‘View menu > Run Spindump’ and then goto Glyphs and do things until the spindump is ready (10 or 30s).
A word on the Wacom and 5k / 4k lag. From what I can gather, both from Wacom support and personal experimentation, the tablets are not mapped to higher res screens and in turn pause during certain movements. I have however not tried the very latest Intuos that just came out.
Many Thanks. Can you send me the .glyphs file, a screencast and your RMX plugin, too?
Hi there, I wonder have you had chance to look at this issue?
Working on a retina 15" MacBook (2016) is fine, but a retina 27" iMac (2017) just feels sluggish all round. It is frustratingly difficult to pinpoint what the problem is, but I notice issues with dragging around points for selection and also occasional zoom and screen redraw.
I removed RMX Tools, but this did not make any difference for me.
Thank you.
We had a lengthy discussion in another thread. I’m quite certain that you have a plugin that causing the slowdown. The latest cutting edge version has an option to start without plugins by holding the opt+shift key when you start the app.