Please test with the nightly build to see if it is still an issue. Thanks.

https://developer.joomla.org/nightly-builds.html

@Quy same, tested again with current nightly build Extremely CPU intensive !!

Joomla! Version | Joomla! 4.0.0-beta8-dev Development [ Mañana ] 2-February-2021 20:02 GMT

Each test ist one client website click (single page load)!

Share your exact PHP info. I'll bet you're missing something and a polyfill is used thus the bad performance

@dgrammatiko attached export settings from metioned joomla instance (including php info)
systeminfo-2021-04-14T23 48 39+02 00.zip

maybe it's easier to debug this on your side. My local setup has these extensions enabled:

Dimitriss-MBP:joomla-cms dgrammatiko$ php -m
[PHP Modules]
bcmath
bz2
calendar
Core
ctype
curl
date
dom
exif
fileinfo
filter
gd
gettext
hash
iconv
imap
intl
json
ldap
libxml
mbstring
mysqli
mysqlnd
openssl
pcntl
pcre
PDO
pdo_mysql
pdo_pgsql
pdo_sqlite
pgsql
Phar
posix
readline
Reflection
session
SimpleXML
soap
sockets
sodium
SPL
sqlite3
standard
tokenizer
xdebug
xml
xmlreader
xmlwriter
xsl
zip
zlib

[Zend Modules]
Xdebug

Please try apply the changes from that PR #31143 then disable "Log Deprecated" in global config.
And tell about results.

The graph itself does not tell anything usfull that we can use for track the issue.
But would be interesting see graph compassion J3 vs J4 on same server.

But would be interesting see graph compassion J3 vs J4 on same server.

First post

but I read it ?

well then, ignore my last sentence ?

@Fedik first post ist directly comparison vs J3 on same server. The different is extremly. Where Joomla 3 is not noticeable at all, joomla 4 strikes out extremely.

Do you have more matrices of the server load? I/O, memory usage, separated Info for Apache and SQL server. What's the timescale? Some more information about the hardware like baremetal or VM (which hypervisor). SSD, how they are connected nvme,SAS,sata?

@Fedik same problem on mentioned PR
@HLeithner dedicated Intel Xeon as mentioned in first post with 32 GB RAM on SSD SATA (not nvme)
memory usage does not strike out noticeably. More infos next...

If it possible to run profiler (eg xdebug) and attach the result, that also would be nice.

Here is Top 10 "slowest methods" from profiler from my test installation (php8, fpm, nfs). When open Dashboard.

Joomla 4:

Joomla 3:

Joomla 3 is ~30% faster, If XDebug not lying.
When disable logging for Joomla 4 it become ~20% faster. (I mean make Log::add() empty :) )

I have several Joomla 4 sites on basic cheap $5 servers at DigitalOcean and Linode and I dont see any such CPU spikes, I also dont see any spikes locally.

I suspect something with their file system set-up

Nic runs Joomla 4 for his live akeeba.com - Im sure if there were such (consistent, replicatable ) spikes we would have heard about it by now ;-)

His blog not his main site ;)

I've been running it for a month on learnjoomla4.com and nothing but joy so far

sloth-theme.site (the only true SPA/PWA ever build with Joomla) runs J4 for a year on a $5 DO VPS and here are some stats

it's really hard to compare different metrics/tools
plus
each one of you have provided different "numbers/graph"

i'm inclined to close this issue...maybe room for https://github.com/joomla/joomla-cms/discussions

Thanks all for your feedback. Our hoster has now started to check further with that issue. I'm with you, it seem not to be a Joomla issue. Anyway, if anything comes up, I will share the problem with you.