We use PLESK on an SuSe Linux 9 plattform. Single CPU 3000+ 1 GB RAM 1 Gbps We host different websites with several subdomains on the Server. One of these subdomains contains an application based on PHP5 with MySQL . The application is in use of about 25 conurrent users. Randomly the application becomes very slow. An action which normaly takes a second takes up to 40 seconds now. In that time the whole server lags and even the other websites are slow. But only for HTTP-Requests. Our we tried to analyse the problem: - HDD only 9% in use - show processes with "top": While a lag appeared no CPU Load for any http or MySQL processes - show network traffic with "iptraf" Nearly no traffic hits the server - show apache status with "apachetop" Normaly 2 requests per second Has somebody any ideas what we can check to find the problem?