I run my three accounts on different browsers so I can have them all up at the same time...between Chrome, IE 11, and Edge, Chrome is consistently the slowest. It is also the most affected by lag from graphics-intensive non-browser games. But the real takeaway here is that it is not a problem on Nutaku's end since whenever I get a hung-up loading screen, the issue is always resolved when I reopen the game in a new tab. I don't know how to solve your particular problem, but at least we know where it isn't happening.
Something else to consider: Whenever I have PeroPero open in another tab, especially after playing a dozen nGachas in that game, everything slows down, most noticably FKG. So I generally close PeroPero these days everytime after I'm done, it's just 2 clicks away to open in a new tab later anyway. Not sure if any other games cause similar issues.
Just scanned my PC for malwares.
Many is found and removed.
Currently testing if it works.
So far don't see any problems.
Hope it continues for eternity.