If your server seems slower than usual, this article will help you identify common causes for both Linux and Windows that may be causing most performance issues. 

1. Check CPU usage

• Log into your server and run top on Linux or open Task Manager (Ctrl + Shift + Esc) on Windows
• Check for any process consuming an unusually high percentage of CPU. If one process is consistently above 80–90%, it might be slowing your server down. 

2. Check memory

• Check the Memory section. If swap usage is high, your server has run out of physical RAM and is using disk space as overflow. Disk is slower than RAM, causing the server to be slow. Consider closing unused applications or upgrading your plan.

3. Check disk activity

On Linux:

Monitor Disk I/O (Input/Output) with “iotop” and Process Details with “htop”:

With the tools  "iotop" and "htop" you can monitor the usage of processes on your server.

• iotop: Focus on which processes are causing the most disk read/write activity, checking if it aligns with expected disk usage. 
• htop: An enhanced version of top with a more intuitive interface, providing detailed views of processes, CPU cores, and memory usage.

On Windows:

Open the Task Manager (Ctrl + Shift + Esc), navigate to the Processes tab, and click the Disk column header to instantly see which programs and background services are hogging your drive.

If iotop/Task Manager confirms unusually high disk activity, upgrading to NVMe storage may improve performance. See Can I add more NVMe storage to my VPS or VDS/Dedicated Server?

4. Check your network connection

We advise you to check with your local internet provider for any known problems in your area.

You can also run the following command on your machine and look for any hops with high response times or timeouts:

• Linux: traceroute <your-server-IP>
• Windows: tracert <your-server-IP>

If delays appear early in the list, the issue is likely with your local network or ISP. If they appear later, it may be closer to the server. In that case, you may want to consider migrating to a region closer to you (see How do I Change My Server's Region?). If you believe a host change within your current region would resolve your issue, please contact support (see steps below).

5. Review system logs

Check your system logs for errors or warnings around the time the slowdown started - these can reveal hardware issues, failed services, or misconfigurations. 

• Linux: Check /var/log/syslog
• Windows: Open Event Viewer (press Windows key + R, type eventvwr, press Enter). Navigate to Windows Logs - System and look for entries marked as Error or Warning around the time the issue started. 

Is the server still slow after checking the above? Please contact our support team with the following information so we can investigate further:

• When did the issue start?
• Which applications or services are affected?
• Screenshots or output from the steps above (CPU, memory, disk usage)
• Run traceroute <your-server-IP> (Linux/Mac) or tracert <your-server-IP> (Windows) and paste the output into your ticket

How do I submit a ticket to Contabo Customer Support?

Ongoing performance monitoring

If you want to catch performance issues before they become a problem, you can use Prometheus and Grafana. This combination lets you collect server metrics over time and visualize them in dashboards, making it easy to spot trends in CPU, memory, and disk usage. 

If you're having trouble accessing the video below, you can also watch it directly on Youtube.