I’ve been having a problem for a while that using Glyphs with the plugin “Show Stem Thickness” makes fans go at full speed. If I launch Glyphs without plugins (option+shift) my laptop is very quiet.
Any fix for the noise issue?
Using the newest Glyphs software in macOS Catalina 10.15.5
Are you sure it is the “Show Stem Thickness” plugin? Can you remove all other plugins and restart Glyphs (you can rename the Plugin Folder, make a new one and copy only the one into it).
Unfortunately, I’m positive that it’s the “Show Stem Thickness” plugin (I haven’t tested with other plugins to see if they reproduce the issue as well though).
I did the following:
Renamed the plugins folder, then created a new folder named “Plugins” and deleted the old folder.
Opened Glyphs and installed the “Show Stem Thickness” plugin.
I then worked on a light type project in Glyphs for about 20 minutes with no other software running. The fans on my computer proceeded to speed up until they reached maximum speed (ca 6000 rpm) and they remained on max speed for the remainder of my work-session.
Then I deleted the plugin from the folder and re-launched Glyphs.
Made sure that no other software was running, and worked on the same type project for 20 minutes. My computer’s fans were barely audible during the entirety of the 20 minutes.
A colleague I’ve spoken to has the exact same issue. It’s very noticeable when the fans run at 6000 rpm, so I’m praying for a fix! 
How much text do you have in your Edit tab?
Five letters. No background images or anything imported. The issue persists if I make a brand new font-file as well.
I assume you made sure you have the latest version of Show Stem Thickness?
Yes, I re-downloaded it from here: https://github.com/RafalBuchner/StemThickness
Can you do a spindump. While the fan is spinning, open Activity Monitor, from the gear button in the toolbar, chose “Spindump” and immediately switch back to Glyphs and keep working until the spindump is finished. The spindump will be a big text file. Send that with email to support at this domain.
Thanks for the spindump. One more question. Is the fan also running if you’re not doing anything? Or only if you use the app?
No, if I’m not doing anything (but have the app open in the background) my computer will remain silent.
Any updates on this?
Did you send a spindump?
Unfortunately, the spindump was not helping.
Ah, too bad 
Thank you dear friends, but unfortunately it has been disabled with the Glyphs update, Has anyone found a solution?
Can you remove and reinstall it from the plugin manager?
Unfortunately, it doesn’t install in the plugin manager and there isn’t even a place where I can remove it. I download and install from Github but it is not visible in installed plugins. Of course, I can install other tools.
The you need it deinstall it manually. From the Scripts menu choose “show scripts folder”. Then you see the Plugins folder. Remove the plugin and restart Glyphs. Then it should work.
It is already installed, but the tool does not work!
Just to be sure, remove it manually and then re-install it from the plugins manager. And restart Glyphs.
Thank you, but I did and the change didn’t happen and it won’t show the tool again.