Vanilla

You probably have too many heavy queries running. Execute this statement and see what queries are running. You may want to tune them down, cache results, etc... I guess you're running a webserver that accesses these databases? Mostly badly written admin tools could be the culprit for such heavy loads:
SHOW PROCESSLIST;
 
Also memory consumption isn't that high for such a big server. Check your buffer sizes, table cache and query cache because maybe you'd tune them to reduce cpu usage. It's a bit of a trade-off since you'll have more memory consumption but since the cpu bottlenecks your server for obvious reasons it's definitely a good deal. More info here: https://dev.mysql.com/doc/refman/8.0/en/memory-use.html and here: https://dev.mysql.com/doc/refman/8.0/en/server-system-variables.html

devIL is open source so you can just download the source, compile it and use it in your client. You should not just replace the dll without proper source adjustments. But you can easily replace devIL includes and compile your own dll. Just use that instead, it'd work without breaking guild mark display.
And no, you do not have any disadvantages. But you can compile the dlls with more recent toolsets and thus benefit from faster dlls and also more recent versions often allow you to use more tools from the library or even have some bugfixes.

I highly recommend switching to utf-8 for client encoding.
Either way the problem you encounter here is mismatching encoding. The client expects a different encoding and therefore cannot display the character properly.
There are also bulk tools that allow you to change the encoding of multiple files. For UTF8 there's for example UTFCast Express which is free.

This means that something is already bound to this address (ip and port). So in this case you either have another program running that listens to the ports of ch2 or ch2 is already running. Can you check with ps -aux if ch2 is already running? Also I saw a critical error from your Ch2 log:
!!! FATAL ERROR !!! multiple MAP_ALLOW setting!!
You may want to have a look at this. It may be the reason why your ch2 freezes.

Maybe it's just a small mistake but did you recompile and replace the core with your new version? And did you double-check that it's added to the list before the NULL, NULL entry? And you saved everything and recompiled the core with the changes? Because it seems like something went wrong, the program can't find the function.

0x3E71C0
for vanilla 2.4.1

10.0 is also stable.
And I find it to be better.
I kinda like the change from gcc to clang and I for myself use 10.0.
But it's a personal thing. I don't think there's a clear "this is better than that"...