Issue Webmail performance interferes Website performance - Tuning tipps?

[cool_sh]

Following situation:
We have a bigger online shop with PHP 7.4 FPM and Nginx + Nginx Cache currently. The performance slows down from time to time, especially when using Webmail (Roundcube) in parallel.

In roundcube timeouts occur, opening mails is as well very slow and at the same time the perfomance of the onlineshop seems to be hit as well.

Activating the IMAP indexes cache for Roundcube was one of the ideas, but it doesn't change anything ( $config['imap_cache'] = 'db'; )

There is only this shop hosted on the VPS, no other customers or domains. System: Plesk Obsidian 18.0.42 Update #1, Linux, CentOS

Questions:
Am I right that Roundcube Webmail can only use PHP 7.4 as the version with plesk is not the newest?
Could chang the FPM to "dedicated FPM" help?
Has anyone hints beside that?

 

[IgorG]

Am I right that Roundcube Webmail can only use PHP 7.4 as the version with plesk is not the newest?

Current version of Roundcube in Plesk is not compatible with PHP 8.1, for example.

 

[Bitpalast]

The performance slows down from time to time, especially when using Webmail (Roundcube) in parallel.

Very unlikely that webmail is the reason. You may perceive it this way, but did you actually check the Linux process list and top/htop/iotop situation at the time when this occurs? Which processes are causing a high load?

 

[cool_sh]

Current version of Roundcube in Plesk is not compatible with PHP 8.1, for example.

That is right but version 1.5 has PHP 8.0 support which the 1.4.x provided with plesk doesn't.

 

[cool_sh]

Thanks Peter for the hint, it seems it is PHP related in some case:-(

$ top PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 11524 xxxxxx 20 0 873232 156200 81504 S 31.8 1.0 0:08.55 php-fpm 11527 xxxxxx 20 0 875196 157452 81488 S 28.8 1.0 0:08.55 php-fpm 11130 xxxxxx 20 0 880088 167968 86760 R 23.5 1.0 0:51.36 php-fpm 11155 xxxxxx 20 0 1229280 174108 94440 R 22.8 1.1 0:49.85 php-fpm 19298 mysql 20 0 5051824 2.7g 9652 S 15.6 17.2 3942:27 mysqld 11528 xxxxxx 20 0 871336 147400 75352 S 15.2 0.9 0:08.93 php-fpm 11242 xxxxxx 20 0 1234156 179160 94076 S 13.6 1.1 0:39.32 php-fpm 11523 xxxxxx 20 0 1210560 129664 70704 S 6.0 0.8 0:03.46 php-fpm