I don't know how to help you reproduce this problem since it is not something that happens all the time. But I'll try :)
As I have noticed the problem is only on articles with a lot of <math> tags and it only appears when the Math mode is selected MathML with SVG or PNG fallback (recommended for modern browsers and accessibility tools).
For example try to edit the Աստիճան (հանրահաշիվ) article on hywiki. Even when editing small sections, sometimes gadgets don't load at all.
If my hardware/software info can help, I'm using Google Chrome 84.0.4147.125 on Windows 10 Home. My laptop has 8 GB ram and runs on AMD Ryzen 3 3200U with Radeon Vega Mobile Gtx. I don't know if this matters or not but, in any case, my internet download is 2.28 Mbps and upload is 0.63 Mbps.