My site hangs due to high php requests

[zzd]

Hello

I'm Dan , new to this forum and I have an issue with my linux. Sorry for being a total noob and not searching but it's 4 am already and I'm really pissed off. Ok , I have a file upload site runing a php script so my visitors can upload their files. The site is hosted on a dedicated linux server (RHE) from EV1 servers and it has a decent connection. Ok , and here's my issue: when more then 15-20 people are accesing the site the same time (no matter they download/upload or just visiting) the site hangs. I won't make public the URL to not be considered that I'm promoting it here. I just need some help to fix this, maybe a php.ini setting ? the current max_execution_time is set to 30 seconds. Or is it an apache setting who causes this problem ? You tell me , I really need some help.

And another issue. I'm using PLESK Control Panel to do misc settings on the site. Another issue here because of my uploading script. The /tmp/ folder is being populated with temporarely files when people upload something. I've set a cronjob proces to delete those files hourly but nothing happens. Here's my crontab conf:

        14      5       *       *       *       /usr/local/psa/bin/mysqldump.sh >/dev/null 2>&1
        7       4       *       *       *       /usr/local/psa/admin/sbin/statistics >/dev/null 2>&1
        */15    *       *       *       *       /usr/local/psa/admin/sbin/backupmng >/dev/null 2>&1
        17      7       *       *       *       /usr/local/psa/admin/bin/php /usr/local/psa/admin/plib/report/autoreport.php --auto daily >/dev/null 2>&1
        17      7       *       *       1       /usr/local/psa/admin/bin/php /usr/local/psa/admin/plib/report/autoreport.php --auto weekly >/dev/null 2>&1
        17      7       1       *       *       /usr/local/psa/admin/bin/php /usr/local/psa/admin/plib/report/autoreport.php --auto monthly >/dev/null 2>&1
        *       1       *       *       *       /root/tmp >/dev/null 2>&1

It's funny since I've setup this job from Plesk and everything should work fine but nothing deletes from /tmp/ folder. And again, when /tmp/ dir. is full, the site hangs.

Any advice is appreciated.

Thanks

[zzd]

no one ?