Getting very slow performance of on prem Exchange 2019 service over the day

Hi MA Momin 
Thank you for reaching out to Microsoft Learn Q&A!     
I understand you're experiencing slow performance with your Exchange Server 2019 recently 

Based on my research, here are some areas you might want to investigate further: 

1. You can use Performance Monitor to track system resource usage such as CPU, memory, and disk activity. This tool provides valuable insights into how your server is performing over time.  For more details, you can refer to Microsoft’s guide:  Troubleshoot issues using Performance Monitor - Windows Server | Microsoft Learn 
2. Running the Get-HealthReport PowerShell command and using the HealthChecker.ps1 script can help identify potential issues with your Exchange environment. 
3. Checking the Event Viewer and IIS logs may reveal warnings or errors that could be contributing to the performance issues. These logs often provide helpful clues for troubleshooting. 

If you have any updates or further questions, please don’t hesitate to reach out.  

Looking forward to hearing from you soon. 

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