When choosing a cloud server to deploy a website, many website owners opt for Japanese cloud servers due to reasons such as low latency access for Asian users, stable hardware environment, and high-quality international bandwidth. However, even high-performance Japanese cloud servers can experience issues like lag, access delays, or slow responses. This can be particularly challenging for novice website owners, who may feel helpless when faced with server performance degradation.

　　First, it's crucial to identify the manifestation of server lag. Lag may manifest as slow webpage loading, delayed API responses, low file upload/download speeds, or lag during SSH remote operations. By observing and recording these phenomena, you can initially determine which layer the problem might be at. For example, if webpages load slowly but SSH connections are normal, the problem may lie in the application or database layer; if SSH operations are also delayed, the problem may lie in the server system or network layer. Identifying the problem's symptoms is the first step in troubleshooting.

　　Network issues are one of the common causes of lag on Japanese cloud servers. Network latency, packet loss, bandwidth limitations, or unstable international connections can all lead to slow access. Beginners can use the ping and traceroute commands for initial troubleshooting. For example, using the command:

ping yourdomain.com
traceroute yourdomain.com

　　You can test the latency and routing path between the server and the client. If you find a high packet loss rate or excessive latency at a certain hop, you may need to contact your cloud service provider to optimize the line or choose a dedicated channel with CN2 lines. For international access, especially when Chinese users access Japanese servers, using optimized lines or CDN acceleration can also significantly improve the access experience.

　　Secondly, insufficient server system resources are also a major cause of lag. CPU, memory, disk I/O, and network bandwidth can all become bottlenecks. Beginners can monitor resource usage in real time using command-line tools. For example, use `top` or `htop` to check CPU and memory usage:

top

　　Alternatively, you can use iostat to check disk I/O:

iostat -xz 5

　　By observing CPU utilization, memory usage, and disk I/O speed, you can determine if there are resource bottlenecks. If the CPU is consistently at 100% usage, there may be performance issues with the application or script; if memory is frequently filled, it may trigger swapping, causing overall system lag; high disk I/O may indicate excessive logs or frequent database read/write operations, impacting overall performance.

　　Application and database layers can also cause server lag. Common application issues include improper Nginx or Apache configuration, insufficient PHP-FPM processes, disabled caching, and slow request processing. Beginners can check the web server status and logs to determine if there are any anomalies. For example, use Nginx commands to check the number of active connections and request processing:

netstat -anp | grep nginx

　　Alternatively, you can check the access logs and error logs of Nginx or Apache to identify high-latency requests or frequent errors:

tail -f /var/log/nginx/access.log
tail -f /var/log/nginx/error.log

　　In terms of databases, unoptimized MySQL or MariaDB can also impact server performance. You can use the `mysqltuner` tool for diagnosis, checking slow queries, cache hit rate, and connection usage. If you find many slow queries or cache misses, you can improve performance by adding indexes, optimizing SQL statements, or enabling query caching.

　　Besides the basic troubleshooting mentioned above, caching strategies are also crucial for improving access speed to Japanese cloud servers. For static resources, you can reduce server load through CDN acceleration or Nginx static caching; for dynamic pages, you can use Redis or Memcached to cache frequently accessed data, reducing database pressure. A beginner can add a caching example to their Nginx configuration:

location /static/ {
    root /var/www/html;
    expires 7d;
    add_header Cache-Control "public";
}

　　In addition, regularly cleaning up log files and unnecessary data, and optimizing disk space, can also prevent lag caused by a full disk or limited I/O. Use the following command to check disk usage:

df -h

　　If a partition is found to be overused, it should be cleaned up or its capacity expanded promptly to ensure stable system operation.

　　Network, firewall, and security policies also affect server performance. New users should check if their firewall configuration is appropriate, avoiding excessive packet filtering rules that could lead to high CPU load. For Japanese cloud servers serving international access, protection policies can be used to prevent DDoS attacks or malicious requests, reducing abnormal server pressure. For example, configuring iptables or the cloud service provider's built-in firewall rules can limit abnormal traffic and improve access stability.

　　If the above measures still do not solve the problem, consider upgrading server configuration or adjusting bandwidth. Japanese cloud servers typically offer flexible CPU, memory, and bandwidth options. Appropriate upgrades based on website traffic and business needs can directly alleviate lag. Furthermore, distributed architecture or load balancing strategies can distribute traffic across multiple servers, improving overall response speed.

　　During troubleshooting, novice website owners should keep records and test step-by-step. It is recommended to check in the following order: "Network → System Resources → Applications/Databases → Caching Policies → Firewall Security → Server Upgrades." This allows for quick bottleneck identification and avoids blindly adjusting configurations that could create new problems. At the same time, by combining online speed test tools or website monitoring tools to track server response time and access speed in real time, the optimization effect can be judged more intuitively.