Frustrations with SLOW interface on Raspberry Pi 4B - 15s++ loading times

Volumio Information

Volumio Version: 2.907 (fresh instance)
Hardware: Raspberry Pi 4B, 2GB RAM
DAC: external USB

Average Raspi temp: ~55 C
Average CPU load: <5%
OS disk: class 10 microSD, 32GB
library: USB HDD, 100GB of FLAC files (only)

Let me just get to the point instead of babbling about how inefficient Volumio is in my setup.
Attached you’re going to find screenshots and Chromium loading test file confirming my problems.

It takes above 15 seconds (often more like 25) to load the playback interface over local 1Gbps LAN. After that, occasionally, when I click thru different options, Volumio feels like it must re-load everything and it again takes another 20-ish seconds every time. Combined, it makes close to impossible to operate Volumio in a reliable and user friendly way.

I made some loading tests for the frontend part of the app (below in the Dropbox link, and on the screenshots attached). Some interesting things emerge from here. For instance that a couple of initial CSS load time is 9 seconds… Meanwhile, close to nothing is going on on the backend side. CPU is almost IDLE, as well as the I/O on the Pi.

I’d like to better understand what is goin on here! How one can proceed from this point? Doing everything I did (probably there’s nothing more I can do to make you guys understand my situation better) I conclude (I might be mistaken) that it’s the Volumio’s fault - the Node backend seems utterly unresponsive despite having resources to its disposal. I hope I’m wrong and I welcome constructive discussion on the topic. Otherwise I’ll need to abandon Volumio. Hence this post; help me to figure out what is going on here.
I have a strong feeling that other people experience similar kind of issues with Volumio…

PS: Initially I assumed that I might have a problem with the disk OS I’m ussing, but now, after trying multiple options (shame USB boot isn’t possible), I’m sure that’s not the case.
PS2: Nothing interesting in the logs, both in Volumio and the underlying Linux.
PS3: Chrome’s *.har file with network loading tests: XXX
PS4: I’m also interested in discussing why the heck my local Volumio makes calls to external CDN, Google and Facebook, just to load it’s interface. Ah, and there’s also Firebase… Oh, boy.
PS5: I’ve been using Volumio for about 5 months now and from my point of view it’s always been slow like that.

OK. For those who will be visiting this topic in the future:

The problematic part that made the whole Volumio unresponsive was an external plugin called miniDLNA. No need to investigate the reported issues further - I’m surre it’s the pluggin which is guilty of messing with the system; I’ll be trying to solve the issues with the plugin’s author.
After disabling the plugin for good and making some additional tests, I can happlily let you know that Volumio is snappy like it should be. Therefore my problem is solved.

The tricky part was to spot that it’s the plugin’s falut (a funny thing is that it’s the only external thing I’ve added to Volumio ever), because it doesn’t squeeze any measurable resources out of my Raspberry Pi. Hence, it must be messing with the system on some level that results in introducing a lot of delays in network connectivity / rendering the interface in the browser. Also, there’s still nothing in the logs, but I’ll try to convince the author to inspect my case.
On the other hand, if any of the Volumio developers are going to stumble upon this post I think it’s worthwhile to figure out why this popular DLNA extension makes Volumio unresponsive.
PS: My miniDLNA version is 1.1.7, but I was experiencing it impacting Volumio negatively for at least a couple of months at this point.

I also recommend all Raspberry Pi users reporting networking and performance problems of their Volumios to check if they have miniDLNA installed and enabled. There’s no way that Volumio is going to be glitching due to performance reasons on Raspi 4 - it has like 10 times more powet than Volumio’s needs.